Cloistered Youth // Unholy Fiend

a creature transforms — 105 cards in the game can cause this (Cloistered Youth is one).

When Cloistered Youth // Unholy Fiend transforms:

1. Sygg, Wanderwine Wisdom // Sygg, Wanderbrine Shield — grants a keyword
2. Neglected Heirloom // Ashmouth Blade — triggers

1 other card cares about it too. These are the ones with the most connections.

life is lost — 3,160 cards in the game can cause this (Cloistered Youth is one).

When Cloistered Youth // Unholy Fiend makes a player lose life:

1. The Master of Lake-town — mills a card
2. Intermediate Chirography — puts a counter on a creature
3. Vilis, Broker of Blood — draws you that many cards
4. Vengeful Warchief — puts a +1/+1 counter on itself
5. Wax-Wane Witness — gets +1/+0
6. Oath of Lim-Dûl — sacrifices an enchantment
7. Marina Vendrell's Grimoire — triggers
8. Lich's Mastery — triggers
9. Lich's Tomb — sacrifices a permanent
10. Gonti's Machinations — puts a counter on a permanent you control

46 other cards care about it too. These are the ones with the most connections.

a Human enters the battlefield — 4,639 cards in the game can cause this (Cloistered Youth is one).

When Cloistered Youth // Unholy Fiend enters:

1. General Kudro of Drannith — hits a graveyard
2. Heronblade Elite — puts a +1/+1 counter on itself
3. Kyler, Sigardian Emissary — puts a +1/+1 counter on itself
4. Thalia's Lieutenant — puts a +1/+1 counter on itself
5. Champion of the Parish — puts a +1/+1 counter on itself
6. Captain of the Mists — untaps itself
7. Erkenbrand, Lord of Westfold — gives +1/+0
8. Beregond of the Guard — gives +1/+1
9. Théoden, King of Rohan — grants double strike
10. Lossarnach Captain — taps a creature an opponent controls

2 other cards care about it too. These are the ones with the most connections.

a creature attacks — 17,934 cards in the game can cause this (Cloistered Youth is one).

When Cloistered Youth // Unholy Fiend attacks:

1. Adaptive Omnitool — searches a library
2. Anthem of Rakdos — gives +2/+0
3. Kindred Discovery — draws you 1 card
4. Invasion of New Capenna // Holy Frazzle-Cannon — puts counters on a permanent
5. Chorale of the Void — brings a card back
6. Alluring Suitor // Deadly Dancer — triggers
7. Saw — sacrifices a creature
8. Gisa's Favorite Shovel — makes an opponent sacrifice a creature
9. Ultima Weapon — kills a creature an opponent controls
10. Total War — kills a creature

181 other cards care about it too. These are the ones with the most connections.

anything attacks — 17,934 cards in the game can cause this (Cloistered Youth is one).

When Cloistered Youth // Unholy Fiend attacks:

1. Far Fortune, End Boss — deals 1 damage
2. Temmet, Naktamun's Will — draws you 1 card
3. Grim Javelineer — gives +1/+0
4. Invisible Woman — triggers
5. Caesar, Legion's Emperor — sacrifices a creature
6. Guide of Souls — triggers
7. Campsite Cuisine — sacrifices a Food
8. Gossip's Talent — triggers
9. Banon, the Returners' Leader — draws and discards
10. Toph, Earthbending Master — puts a counter on a permanent

111 other cards care about it too. These are the ones with the most connections.

a creature blocks — 17,934 cards in the game can cause this (Cloistered Youth is one).

When Cloistered Youth // Unholy Fiend blocks:

1. Mage Hunters' Onslaught — makes a player lose 1 life
2. Carnage Gladiator — makes a player lose 1 life
3. Barrow-Blade — strips abilities
4. Heat of Battle — deals 1 damage
5. Tide of War — sacrifices a creature
6. Dead-Iron Sledge — kills a creature
7. Dwindle — kills a creature
8. Shield of the Righteous — triggers

20 other cards care about it too. These are the ones with the most connections.

a creature deals combat damage — 17,934 cards in the game can cause this (Cloistered Youth is one).

1. Primo, the Unbounded — When Cloistered Youth // Unholy Fiend deals combat damage, Primo, the Unbounded makes a token

197 other cards care about it too. These are the ones with the most connections.

a nontoken creature attacks — 17,934 cards in the game can cause this (Cloistered Youth is one).

When Cloistered Youth // Unholy Fiend attacks:

1. Mardu Ascendancy — makes a token
2. Basri Ket — makes a token
3. Militia's Pride — makes a token

a creature enters the battlefield — 19,800 cards in the game can cause this (Cloistered Youth is one).

When Cloistered Youth // Unholy Fiend enters:

1. Slash, Reptile Rampager — deals 2 damage
2. The Neutrinos — gets +1/+0
3. Wingnut, Bat on the Belfry — grants flying, haste and menace
4. Aetherstorm Roc — puts a counter on a permanent you control
5. Raphael, Most Attitude — exiles a card from your library

306 other cards care about it too. These are the ones with the most connections.

anything enters the battlefield — 26,499 cards in the game can cause this (Cloistered Youth is one).

1. Prowl, Stoic Strategist // Prowl, Pursuit Vehicle — When Cloistered Youth // Unholy Fiend enters, Prowl, Stoic Strategist // Prowl, Pursuit Vehicle puts a +1/+1 counter on itself

41 other cards care about it too. These are the ones with the most connections.