Ugin's Mastery

a creature is turned face up — 238 cards in the game can cause this (Ugin's Mastery is one).

1. Printlifter Ooze — When a creature is turned face up thanks to Ugin's Mastery, Printlifter Ooze makes a token
2. Experiment Twelve — When a creature is turned face up thanks to Ugin's Mastery, Experiment Twelve puts its power counters on a permanent
3. Pyrotechnic Performer — When a creature is turned face up thanks to Ugin's Mastery, Pyrotechnic Performer deals its power damage
4. Pine Walker — When a creature is turned face up thanks to Ugin's Mastery, Pine Walker untaps a permanent
5. Fugitive Codebreaker — When Fugitive Codebreaker is turned face up thanks to Ugin's Mastery, it draws and discards
6. Fatal Mutation — When a creature is turned face up thanks to Ugin's Mastery, Fatal Mutation kills it

an enchantment is cast — 3,673 cards in the game can cause this (Ugin's Mastery is one).

When Ugin's Mastery is cast:

1. Hallowed Haunting — makes a token
2. Daxos the Returned — puts a counter on a permanent
3. Tatsunari, Toad Rider — makes a token
4. Sythis, Harvest's Hand — gains you 1 life
5. Sigil of the Empty Throne — makes a token
6. Dawnhart Geist — gains you 2 life
7. Herald of the Pantheon — gains you 1 life
8. Kami of Transience — puts a +1/+1 counter on itself
9. Argothian Enchantress — draws you 1 card
10. Mesa Enchantress — draws you 1 card

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

a nontoken enchantment enters the battlefield — 3,691 cards in the game can cause this (Ugin's Mastery is one).

1. Historian's Boon — When Ugin's Mastery enters, Historian's Boon makes a token

an enchantment enters the battlefield — 3,743 cards in the game can cause this (Ugin's Mastery is one).

When Ugin's Mastery enters:

1. Calix, Guided by Fate — puts a counter on a creature
2. Elvish Archivist — draws you 1 card
3. Victor, Valgavoth's Seneschal — surveils
4. Strength from the Fallen — gives +X/+X, where X is the number of creature cards in your graveyard
5. Doomwake Giant — shrinks a creature by -1/-1
6. Cacophony Unleashed — turns something into a creature
7. Ghostly Dancers — makes a token
8. Thassa's Devourer — mills a card
9. Killian, Decisive Mentor — taps a creature
10. Thoughtrender Lamia — makes an opponent discard a card

59 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.

1. Eldrazi Mimic — When Eldrazi Mimic attacks, Ugin's Mastery turns something into a creature
2. Abstruse Archaic — When Abstruse Archaic attacks, Ugin's Mastery turns something into a creature
3. Twins of Discord — When Twins of Discord attacks, Ugin's Mastery turns something into a creature
4. Omnath, Locus of the Void — When Omnath, Locus of the Void attacks, Ugin's Mastery turns something into a creature
5. Blight Herder — When Blight Herder attacks, Ugin's Mastery turns something into a creature
6. Old Thrush — When Old Thrush attacks, Ugin's Mastery turns something into a creature
7. Skittering Cicada — When Skittering Cicada attacks, Ugin's Mastery turns something into a creature
8. Thought-Knot Seer — When Thought-Knot Seer attacks, Ugin's Mastery turns something into a creature
9. Cryptic Trilobite — When Cryptic Trilobite attacks, Ugin's Mastery turns something into a creature
10. Mysterious Egg — When Mysterious Egg attacks, Ugin's Mastery turns something into a creature

17,924 other cards cause it too. These are the ones with the most connections.

anything enters the battlefield — 26,499 cards in the game can cause this (Ugin's Mastery is one).

1. Sokka, Bold Boomeranger — When Sokka, Bold Boomeranger enters thanks to Ugin's Mastery, it draws and discards
2. Hei Bai, Forest Guardian — When Hei Bai, Forest Guardian enters thanks to Ugin's Mastery, it puts a Shrine onto the battlefield

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