191Challenge Profile / JP
KazuYagami#JP1
Latest Riot challenge data cached by Lolytics.
Updated 1d ago
10,750
Challenge crystal
Platinum
Overall challenge tier
277
277 cached rows
May 7
Riot payload refresh
Challenge Progress
Earned and progressed challenges
277 cached challenges
In Delightful Agony: 2023
Top 0% | 28
Get First Bloods
Overwhelming Presence
#4,431 | Top 0.1% | 6
#3,439
Ladder placement
Field Medic
#9,687 | Top 0.3% | 3,534,706
#9,687
Ladder placement
I Shall Feast: 2023
#11,132 | Top 0.3% | 2,541
#11,132
Ladder placement
Brave The Darkness: 2023
#30,391 | Top 0.8% | 1,278
#30,391
Ladder placement
Got Your Back: 2023
#17,827 | Top 0.5% | 218
#17,827
Ladder placement
Gets The Wurm
#58,225 | Top 1.5% | 98
#58,225
Ladder placement
Death Fears Me: 2023
#22,992 | Top 0.6% | 24
#22,992
Ladder placement
A Honeyfruit a Day: 2024 Split 3
Top 5.8% | 49,794
Restore health through map-based healing sources
Immediate Immobilization: 2023
#9,632 | Top 0.3% | 10,580
#9,632
Ladder placement
Darkness is Everywhere
#50,462 | Top 1.3% | 4,509
#50,462
Ladder placement
Goodbye to the Darkness!
#61,596 | Top 1.6% | 2,865
#61,596
Ladder placement
The Jukes!
#248,894 | Top 6.5% | 2,861
#248,894
Ladder placement
Dinner's Ready
#64,254 | Top 1.7% | 2,153
#64,254
Ladder placement
Making the Dream Work
#55,930 | Top 1.5% | 979
#55,930
Ladder placement
Breakable: 2023
#26,839 | Top 0.7% | 656
#26,839
Ladder placement
Wurm Fishing
#68,651 | Top 1.8% | 414
#68,651
Ladder placement
Farm Champs not Camps
#28,876 | Top 0.7% | 344
#28,876
Ladder placement
Jungle Diff
#22,246 | Top 0.6% | 328
#22,246
Ladder placement
Two Shells are Better Than One
#36,469 | Top 0.9% | 211
#36,469
Ladder placement
Global Defense System
#360 | Top 0.1% | 179
#360
Ladder placement
DPS Threat
#441 | Top 0.1% | 167
#441
Ladder placement
Incredible Value
#30,633 | Top 0.8% | 117
#30,633
Ladder placement
Incandescent
Top 5.4% | 66
Obtain <em>mage champions</em>
Unkillable Demon King
#45,565 | Top 1.2% | 57
#45,565
Ladder placement
No Capstone Unturned
Top 4.3% | 52
Reach Gold tier on Capstones
Trust Nothing But Me: 2023
#3,848 | Top 0.1% | 51
#3,848
Ladder placement
It Has "Ultimate" In the Name!
#27,449 | Top 0.7% | 51
#27,449
Ladder placement
Rise Above the Rest: 2023
#39,508 | Top 1% | 46
#39,508
Ladder placement
Invulnerable
Top 6% | 46
Obtain <em>tank champions</em>
Clean Clears
#29,564 | Top 0.8% | 42
#29,564
Ladder placement
Inspiring
Top 7.7% | 38
Obtain <em>support champions</em>
Lightning Round
#34,798 | Top 0.9% | 32
#34,798
Ladder placement
Immortal
Top 4% | 17
Win a game with more than eight kills without dying
We're Good Over Here
#56,882 | Top 1.5% | 12
#56,882
Ladder placement
Open Victory
Top 6.4% | 10
Win with an open nexus
They Just... Don't... DIE!
#20,130 | Top 0.5% | 10
#20,130
Ladder placement
Victorious Regalia
Top 2.3% | 9
Collect <em>victorious champion skins</em>
Hold That Pose
#109,555 | Top 2.8% | 8
#109,555
Ladder placement
Made My Mark: 2023
Top 5.1% | 2
Win after being down 15 kills
It's All Me: 2023
#22,324 | Top 0.6% | 1
#22,324
Ladder placement
First To Fall: 2023
#26,591 | Top 0.7% | 1
#26,591
Ladder placement
Flawless Victory
Top 8.3% | 1
Win a Perfect Game
Get Paid, and Get Out
Top 5.4% | 9,462,389
Earn gold
Wise Master
Top 3% | 2,661,394
Earn Mastery Points
One-Trick
Top 3.1% | 434,020
Gain Mastery Points on a single champion
Ability Abuse
Top 5.3% | 244,679
Use Abilities
Immediate Immobilization
Top 4.8% | 21,556
Immobilize enemies
Team Takedown
Top 4.5% | 8,699
Get picks with at least one ally
Above-Average Assistance
Top 4% | 7,364
Get Assists
Stun n Gun
Top 3.6% | 4,256
Immobilize then take down an enemy with an ally
Go Where You Please
Top 5.4% | 2,164
Tank three immobilizing effects in a fight and survive
Scuttle Along Now
Top 1.9% | 2,150
Kill scuttle crabs
Snow Day
Top 3.9% | 2,131
Hit snowballs on champions
Medal of Honor
Top 4.2% | 1,865
Earn progress from challenges in the Executioner, Commando, Resourceful, and Mystic groups
Turret Toppler
Top 4.6% | 1,552
Destroy turrets
2023 Seasonal
Top 4.5% | 1,375
Earn progress from challenges in the 2023 Seasonal group
Lizard Hunting
Top 3.7% | 1,298
Take down Dragons
Captain
Top 3.4% | 1,000
Earn progress from challenges in the Strategy, Demolition, Synergy, and Team Spirit groups
Determination
Top 5.8% | 985
Earn progress from challenges in the Monster Hunter, Steadfast, and Symbiosis groups
Master of the Rift
Top 6.1% | 870
Play Summoner's Rift Games
Buff Burglar
Top 1.7% | 763
Take enemy buffs
Commando
Top 3.3% | 620
Earn progress from challenges in the Commando group
Shell Collecting
Top 2.4% | 573
Take down Rift Heralds
Champion
Top 8.1% | 540
Earn progress from challenges in the Champion group
Killing Spree Spree
Top 5.2% | 460
Get killing sprees
Movin' On Up
Top 2.2% | 417
Win ranked games in Solo/Duo or Flex queue
Resourceful
Top 5.1% | 405
Earn progress from challenges in the Resourceful group
The Brush Has Eyes
Top 4.6% | 404
Finish a game up 20% Vision Score
Strategy
Top 4.6% | 400
Earn progress from challenges in the Strategy group
KDA Player
Top 2.1% | 329
Get a KDA over 3 in Solo/Duo Queue
Monster Hunter
Top 5.3% | 320
Earn progress from challenges in the Monster Hunter group
Ward Ward-en
Top 6.1% | 298
Protect wards
Target Secured
Top 1.8% | 286
Secure Epic Monsters with the enemy jungler nearby
Baron Power Play
Top 5.2% | 257
Generate 2500 gold advantage with Baron Buff
Steadfast
Top 6.8% | 245
Earn progress from challenges in the Steadfast group
Top Performer
Top 5.4% | 244
Earn S- grades or higher
Perfect Aim: 2023
Top 2.9% | 241
Hit snowballs on champions
Symbiosis
Top 7% | 240
Earn progress from challenges in the Symbiosis group
Mystic
Top 5% | 220
Earn progress from challenges in the Mystic group
Visionary
Top 6% | 220
Earn progress from challenges in the Visionary group
Perfection
Top 5.3% | 215
Earn progress from challenges in the Perfection group
Adept
Top 4.9% | 215
Earn progress from challenges in the Adept group
Outmanned, Never Outgunned: 2023
Top 3.3% | 176
Secure kills while outnumbered
Emotive
Top 3.2% | 160
Obtain emotes
Team Spirit
Top 4.5% | 155
Earn progress from challenges in the Team Spirit group
Spice of Life
Top 6.7% | 148
Obtain <em>champions</em>
On Another Level
Top 3.9% | 138
Be up three more levels than role opponent at any point
Three Buffed
Top 0.6% | 68
Take 3 of the first 4 buff camps
Indomitable
Top 6.6% | 68
Obtain <em>fighter champions</em>
Clutch Steal
Top 1.1% | 63
Steal Epic monsters
TY for Leash
Top 1% | 56
Steal an Epic Monster without Smite
Soul Sweep
Top 5.3% | 55
Claim Dragon Souls 4-0
Lethal Efficiency
Top 3% | 44
Kill 80 minions within 10 minutes
Invisible
Top 6.6% | 42
Obtain <em>assassin champions</em>
All Random All Flawless
Top 4.4% | 42
Earn S grades or higher
Can't Miss
Top 4% | 36
Land 20 skillshots before seven minutes
Ingenious
Top 8.9% | 29
Obtain <em>marksman champions</em>
Plant Tactics
Top 3.2% | 23
Use blast cones to escape enemies
Meat Shield
Top 2.8% | 22
Win the game taking at least 35% of team damage
Ward Hunter
Top 2.9% | 15
Destroy 10 wards before 20 minutes
Nice Try: 2024 Split 2
Top 6.9% | 13
Kill enemies under your own turret
Can of Wurms
Top 10.7% | 9
Kill three Barons in a single game
Nowhere to Hide
Top 3.6% | 5
Win with a 5-stack of <em>champs with 3+ global abilities</em>
Prodigy
Top 7.4% | 4
Become Legendary within 15 minutes
Ladder Climber
Top 0.9% | 3 / 9
Earn rank in Solo/Duo Queue
Global Defense System: 2024 Split 3
Top 7.2% | 2
Have a control ward in enemy jungle for 65+% of the game
Draconic Extinction
Top 9.6% | 1
Kill two Elder Dragons in a single game
Everyone Pays!
Top 5.8% | 122,147
Earn bounty gold
Do These Things Have Souls?
Top 7.8% | 58,973
Kill minions
Dine In
Top 1.6% | 43,105
Kill jungle monsters in your jungle
It was a... Near-Hit
Top 4.5% | 30,689
Dodge skillshots
Another Day, Another Bullseye
Top 4.3% | 22,396
Hit skillshots on champions
Farm Champs Not Minions
Top 4.1% | 15,166
Get Takedowns
Dine Out
Top 1.6% | 6,798
Kill jungle monsters in the enemy jungle
Hard Day's Killin'
Top 7.3% | 3,811
Get Kills
EXPERTISE
Top 6.9% | 2,850
EXPERTISE capstone
TEAMWORK
Top 5.2% | 2,795
TEAMWORK capstone
VETERANCY
Top 6.2% | 2,415
VETERANCY capstone
IMAGINATION
Top 6.2% | 1,390
IMAGINATION capstone
Give 'em Shell, Shelly
Top 4.7% | 1,310
Take turrets with Rift Herald
COLLECTION
Top 5.8% | 1,300
COLLECTION capstone
Might
Top 6% | 1,075
Earn progress from challenges in the Flair, Behemoth, Slayer, and Predator groups
Brush Fanatic
Top 7.6% | 1,060
Get takedowns with an ally after hiding in brush for 3+s
ARAM Authority
Top 7.1% | 865
Earn progress from challenges in the ARAM Warrior, ARAM Finesse, and ARAM Champion groups
Ascendant
Top 8.2% | 775
Earn progress from challenges in the Domination, Unrivaled, and Perfection groups
No Hiding
Top 4.9% | 743
Kill enemies near one of their turrets
Wave Goodbye
Top 13.9% | 732
Kill 20 minions within 3 Seconds
Insec-urity Breach
Top 6.4% | 723
Knock back enemies to your team and get a takedown
No Quarter
Top 6.8% | 681
Kill champions under their own turret
Never Tell Me the Odds
Top 5.4% | 642
Get kills while outnumbered
Harmony
Top 4.2% | 540
Earn progress from challenges in the Harmony group
Nice Try
Top 6.5% | 451
Kill enemies under your own turret
Cleverness and Creativity
Top 6.4% | 445
Earn progress from challenges in the Style, Innovation, and Tactician groups
Predator
Top 3.2% | 425
Earn progress from challenges in the Predator group
Executioner
Top 7.7% | 400
Earn progress from challenges in the Executioner group
Mastermind
Top 7.3% | 335
Earn progress from challenges in the Cornerstone and Visionary groups
Fun with Friends
Top 6% | 323
Play games with a group
Multikill Madness
Top 6% | 310
Get Multikills
ARAM Champion
Top 6.6% | 290
Earn progress from challenges in the ARAM Champion group
ARAM Warrior
Top 9% | 270
Earn progress from challenges in the ARAM Warrior group
Flair
Top 8.3% | 245
Earn progress from challenges in the Flair group
NA-RAM
Top 4.8% | 243
Win games
Damage Dispenser
Top 7.1% | 242
Deal over 700 Damage Per Minute
Connoisseur
Top 3.2% | 240
Earn progress from challenges in the Connoisseur group
Magnum Opus
Top 4.2% | 230
Earn progress from challenges in the Magnum Opus group
Innovation
Top 6.1% | 230
Earn progress from challenges in the Innovation group
Always On Time
Top 1.3% | 228
Kill Epic Monsters within 30 seconds of spawn
Synergy
Top 7% | 225
Earn progress from challenges in the Synergy group
Overachiever
Top 5.9% | 215
Earn progress from challenges in the Overachiever group
2024 Seasonal: Split 3
Top 7.5% | 215
Earn points from challenges in the 2024 Seasonal: Split 3 group
Domination
Top 7.5% | 215
Earn progress from challenges in the Domination group
Unrivaled
Top 6.7% | 205
Earn progress from challenges in the Unrivaled group
Been Here a While
Top 7.1% | 190
Increase your summoner level
ARAM Finesse
Top 5.3% | 185
Earn progress from challenges in the ARAM Finesse group
Guru
Top 2.8% | 160
Earn progress from challenges in the Guru group
Flawless Ace
Top 6.6% | 148
Ace the enemy team with no allied deaths
Golden
Top 6.4% | 146
Have more than 450 gold per minute in a game
Slayer
Top 6.1% | 145
Earn progress from challenges in the Slayer group
Icon of the Rift
Top 5.9% | 145
Obtain Summoner Icons
A Drake and a Hard Place
Top 5.1% | 145
Kill opponents with help from an Epic monster
Darkness Distributer
Top 3.9% | 144
Take down the most wards in the game
Can Run, Can't Hide: 2023
Top 3.5% | 138
Kill enemies near one of their turrets
Bouncer
Top 4.3% | 128
Get the highest crowd control score in the game
Treasure
Top 4.7% | 125
Earn progress from challenges in the Treasure group
Fashion Forward
Top 5.1% | 100
Collect champion skins
Behemoth
Top 7.7% | 100
Earn progress from challenges in the Behemoth group
Stun n Gun: 2024 Split 2
Top 6.1% | 94
Immobilize then takedown an enemy with an ally
Challenges are Forever
Top 4.3% | 91
Reach Diamond tier on different challenges
Crab Wrangler
Top 1.5% | 90
Take both of the first scuttle crab spawns
Alcove Gaming
Top 4.9% | 84
Take down opponents in the alcove
Lane Domination
Top 6.9% | 81
Be up 20% gold and XP at 14min
Style
Top 7.9% | 80
Earn progress from challenges in the Style group
Shoddy Construction
Top 6.8% | 76
Take down the first turret
Dragon On Too Long
Top 4.1% | 75
Take down first dragon before eight minutes
Bloodcrazed
Top 7.3% | 70
Get First Bloods
Target Selection
Top 6.7% | 68
Take down junglers near a damaged Epic Monster
No Hiding: 2024 Split 3
Top 3.9% | 63
Kill enemies near one of their own turrets
Entitled
Top 5.4% | 60
Earn titles from challenges
Level 1 Fiesta
Top 5.4% | 59
Get takedowns before jungle camps spawn
Bad Medicine
Top 4.3% | 47
Kill enemies recently healed by a health pack
Lane Command
Top 7.6% | 43
Be up 20% gold and XP at 7min
Uninhibited
Top 8.6% | 40
Win after losing an inhibitor
Legendary Legend
Top 6.6% | 40
Become Legendary
Nullify the Void: 2024 Split 2
Top 5.6% | 33
Takedown Void Monsters
Rapid Demolition
Top 3.8% | 23
Take the first turret before 5 min
Forever Triumphant
Top 1.6% | 7
End season splits ranked Gold or higher
Right Under Their Noses
Top 7.4% | 7
Recall while unseen by a nearby champion
Darkness Distributor: 2024 Split 2
Top 5.1% | 5
Takedown the most wards in a game
Comeback Kids
Top 6.6% | 4
Win after being down 15 kills
Who Needs 'Em
Top 14.5% | 3
Win a game despite an AFK teammate
Team Diff
Top 6.1% | 3
Score aces between minion spawn and 15 minutes
We Protec
Top 2.7% | 3
Win with a 5-stack of 3+ <em>champs with heals or shields.</em>
Get Over Here
Top 3.8% | 3
Win with a 5-stack with 3+ <em>champs with displacements</em>
Epic Steal
Top 1.6% | 2
Steal two Epic Monsters in one game
Free Money
Top 7.2% | 14,794 / 17,000
Kill minions
Little Inanimate Spies
Top 10% | 3,559 / 3,750
Place Stealth Wards
Alliance
Top 3% | 665 / 1,030
Earn progress from challenges in the Clash, Synchronicity, Harmony, and Globetrotter groups
Solo Bolo
Top 9.1% | 626 / 1,000
Get solo kills
Sage
Top 5.4% | 465 / 560
Earn progress from challenges in the Guru, Virtuoso, and Ace groups
That Was Close
Top 3.2% | 352 / 375
Save an ally with a heal or shield
2024 Seasonal: Split 2
Top 7.5% | 200 / 215
Earn progress from challenges in the 2024 Seasonal: Split 2 group
Ace
Top 6.8% | 135 / 160
Earn progress from challenges in the Ace group
Mid Diff
Top 4.1% | 81 / 100
Win games as Mid
Leading by Example
Top 4.4% | 76 / 90
Get an assist streak of 12+ without dying
Splitpush Strategy
Top 7.7% | 68 / 180
Take side lane turrets solo without dying
Synchronicity
Top 5.7% | 60 / 80
Earn progress from challenges in the Synchronicity group
Pain Prescriber
Top 11.2% | 43 / 50
Deal the most damage to champions in the game
Shattered Plates
Top 10.2% | 42 / 45
Destroy turrets before plates fall
Masterful Performance
Top 5.3% | 42 / 75
Reach Masters tier on different challenges
The Most Dangerous Game
Top 3.7% | 31 / 35
As jungler, kill the enemy jungler in their jungle before 10 minutes
Not Even Close
Top 25.1% | 31
Survive champion combat on single digit health
All Random All Champions
Top 4.3% | 31 / 50
Earn an S- grade on <em>different champions</em>
Fashionista
Top 4.9% | 29 / 30
Collect chromas
Aggressive Positioning
Top 7.9% | 28 / 35
Get multikills after flashing towards an enemy
Active Participant
Top 2.6% | 28 / 50
Have over 90% Kill Participation in games
Get On My Level
Top 8.1% | 27 / 30
Get takedowns after gaining an early level advantage
One Stone
Top 8.6% | 21
Kill two players with one ability cast
Ward Skin Collector
Top 8.8% | 19 / 20
Obtain ward skins
Multi-Weapon Master
Top 5.2% | 14 / 16
Win with <em>different mythic items</em>
Not Even a Scratch
Top 10.9% | 13 / 15
Take 10k damage in a fight and survive
Let's Make This Quick
Top 19.1% | 6
Destroy the enemy nexus in less than 15 minutes
Winhibitors
Top 10.7% | 5
Destroy all three enemy inhibitors in under 25 minutes
Happy Feet
Top 10.4% | 5
Dance with the Rift Herald in the enemy base
That Drip
Top 6.4% | 4 / 7
Collect many skins for a single champion
No Loyalty Among Dragons
Top 10.6% | 3
Take Elder Dragons when enemy has the Dragon Soul
ARAM Legend
Top 8% | 3
Go Legendary
Solo Carry
Top 8.7% | 1
Deal 40%+ of your team's champion damage
Virtuoso
Top 5.2% | 90 / 100
Earn progress from challenges in the Virtuoso group
Power Pair
Top 2.6% | 68 / 100
Win with a premade party of two in a ranked queue
Fashionably Late
Top 4.1% | 60 / 100
Get a takedown after teleporting to a >4 champion fight
Demolition
Top 13.1% | 45 / 50
Earn progress from challenges in the Demolition group
Cornerstone
Top 10.5% | 40 / 50
Earn progress from challenges in the Cornerstone group
Tactician
Top 13.8% | 40 / 50
Earn progress from challenges in the Tactician group
Vintage Look
Top 4.5% | 30 / 40
Collect <em>legacy champion skins</em>
Go Shelly Go!
Top 1.8% | 26 / 35
Take 2 turrets with the same Rift Herald
All-Seeing
Top 7.3% | 22 / 25
Have over 2 vision score per minute
Master the Enemy (Legacy)
Top 2.5% | 17 / 25
Earn Mastery 7 on <em>different champions</em>
Support Subsidy
Top 10.6% | 16 / 25
Fully complete your support quest in 14 minutes
Master Mage (Legacy)
Top 1.1% | 13 / 18
Get Mastery 7 on different <em>mages</em>
Blink and You'll Miss It
Top 8.6% | 11 / 15
Kill champions from full health in 1.5 seconds
Invincible
Top 7.3% | 10 / 15
Win without dying with <em>different champions</em>
Nowhere is Safe
Top 15.7% | 8
Take down champions in their fountain
Flame Horizon
Top 8.4% | 7
Win games with 100+ more CS than role opponent
Master Tank (Legacy)
Top 2.1% | 5 / 10
Get Mastery 7 on different <em>tanks</em>
Master Support (Legacy)
Top 2.2% | 5 / 10
Get Mastery 7 on different <em>supports</em>
Death Incarnate
Top 15.3% | 4
Take down 12 champions within 15 minutes
Making History As 5: 2023
Top 2.9% | 3 / 4
Get wins with a premade of 5
Damage Sponge
Top 11.8% | 1
In one fight, get kills while tanking all five enemies and survive
Master Yourself
Top 5.5% | 28 / 30
Earn Mastery 5 on <em>different champions</em>
Jack of All Champs
Top 9.5% | 26 / 50
Win games with <em>different champions</em>
Fancy Garb
Top 9.5% | 23 / 25
Collect <em>epic champion skins</em>
Champion Ocean: 2024 Split 3
Top 7.4% | 14 / 15
Win games with <em>different champions</em>
The Fire Rises: 2024 Split 2
Top 8.6% | 11
Collect Infernal Cinders
Perfectionist
Top 12.2% | 10 / 15
Earn an S+ grade with <em>different champions</em>
Superior Supporting
Top 9.2% | 10 / 25
Finish your support quest faster than your opponent
Master Fighter (Legacy)
Top 2.6% | 6 / 12
Get Mastery 7 on different <em>fighters</em>
Formal Attire
Top 4.9% | 5 / 6
Collect <em>mythic champion skins</em>
Recursive
Top 5.4% | 5 / 10
Complete collection challenges
Master Mage
Top 1.4% | 5 / 12
Get Mastery 10 on different <em>mages</em>
Top Performer: 2024 Split 2
Top 6.9% | 4 / 7
Earn S- grade or higher
Haute Couture
Top 3.6% | 2 / 3
Collect <em>ultimate champion skins</em>
Free Ticket to Base
Top 10.2% | 1
Execute to turret before 10 min
Pop Goes the Poro
Top 6.9% | 1
Cause a Poro to explode
Top Diff
Top 11.6% | 29 / 30
Win games as Top
Support Diff
Top 11.3% | 15 / 30
Win games as a Support
Master the Enemy
Top 4.9% | 6 / 7
Earn Mastery 10 on <em>different champions</em>
Best Friends Forever
Top 13.5% | 3 / 5
Get wins with a premade of 5
Legendary Wardrobe
Top 14.4% | 2 / 3
Collect <em>legendary champion skins</em>
Master Assassin (Legacy)
Top 7.8% | 2 / 5
Get Mastery 7 on different <em>assassins</em>
Master Tank
Top 4.4% | 2 / 3
Get Mastery 10 on different <em>tanks</em>
Master Support
Top 4.6% | 2 / 3
Get Mastery 10 on different <em>supports</em>
Ten Minute Turret
Top 14.4% | 1 / 2
Destroy the first turret in under 10 minutes
Master Assassin
Top 5.1% | 1 / 5
Get Mastery 10 on different <em>assassins</em>
Master Fighter
Top 5.4% | 1 / 5
Get Mastery 10 on different <em>fighters</em>
Dedicated Master: 2024 Split 3
Top 8.9% | 1 / 3
Earn Mastery Milestones
Pocket Picks: 2024 Split 3
Top 100% | 1
Complete a Mastery Set