Hidden Horror

a Horror deals combat damage — 382 cards in the game can cause this (Hidden Horror is one).

1. Captain N'ghathrod — When Hidden Horror deals combat damage, Captain N'ghathrod mills a card

a nontoken creature is sacrificed — 1,714 cards in the game can cause this (Hidden Horror is one).

When you sacrifice Hidden Horror:

1. Fumulus, the Infestation — makes a token
2. Bag of Devouring — exiles it

a creature is sacrificed — 1,741 cards in the game can cause this (Hidden Horror is one).

When you sacrifice Hidden Horror:

1. Ziatora, the Incinerator — deals that creature's power damage
2. Dina, Essence Brewer — draws you 1 card
3. Fleshtaker — gains you 1 life
4. Body Dropper — puts a +1/+1 counter on itself
5. Smothering Abomination — draws you 1 card
6. Kels, Fight Fixer — draws you 1 card
7. Caesar, Legion's Emperor — triggers
8. Grist, the Hunger Tide — kills a creature or planeswalker an opponent controls
9. Cabal Therapist — triggers
10. Rakdos, the Muscle — exiles a card from an opponent's library

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

a card is discarded — 2,042 cards in the game can cause this (Hidden Horror is one).

When Hidden Horror makes a player discard a card:

1. Ivora, Insatiable Heir — puts a +1/+1 counter on itself
2. Cool but Rude — deals 2 damage
3. Containment Construct — brings a card back
4. Moonstone, Harsh Mistress — brings a card back
5. Lazotep Chancellor — puts 2 counters on a Zombie or Army
6. Magmakin Artillerist — deals that much damage
7. Inti, Seneschal of the Sun — exiles a card from your library
8. Pitchstone Wall — sacrifices itself
9. Currency Converter — exiles it
10. Hostile Investigator — triggers

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

a creature in a graveyard — 2,769 cards in the game can cause this (Hidden Horror is one).

When Hidden Horror is in the graveyard:

1. Chainer, Dementia Master — can bring it back
2. Havengul Lich — can bring it back
3. Liliana the Repentant — can bring it back
4. Paleoloth — can bring it back
5. Chainer, Nightmare Adept — can bring it back
6. Banon, the Returners' Leader — can bring it back
7. Surgical Suite // Hospital Room — can bring it back
8. Sword of Light and Shadow — can bring it back
9. Necromantic Thirst — can bring it back
10. Krile Baldesion — can bring it back

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

a nontoken creature dies — 2,769 cards in the game can cause this (Hidden Horror is one).

When Hidden Horror dies:

1. Zahur, Glory's Past — makes a token
2. Liesa, Forgotten Archangel — brings a card back
3. Avacyn, Angel of Horror — brings a card back
4. Yedora, Grave Gardener — brings a card back
5. Nim Deathmantle — brings a card back
6. Valkyrie's Call — brings a card back
7. Decaying Soil — brings a card back
8. High-Society Hunter — draws you 1 card
9. Liliana, Heretical Healer // Liliana, Defiant Necromancer — flickers itself
10. Body Launderer — draws and discards

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

a creature dies — 2,830 cards in the game can cause this (Hidden Horror is one).

When Hidden Horror dies:

1. Pious Evangel // Wayward Disciple — makes each opponent lose 1 life
2. Daxos, Blessed by the Sun — gains you 1 life
3. Elas il-Kor, Sadistic Pilgrim — makes each opponent lose 1 life

458 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 (Hidden Horror is one).

1. Shaun, Father of Synths — When Hidden Horror attacks, Shaun, Father of Synths makes a token

149 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 (Hidden Horror is one).

1. Chorale of the Void — When Hidden Horror attacks, Chorale of the Void brings a card back

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