Underwater Tunnel // Slimy Aquarium

a creature is milled — 14 cards in the game can cause this (Underwater Tunnel is one).

When a creature makes a player mill a card thanks to Underwater Tunnel // Slimy Aquarium:

1. Zellix, Sanity Flayer — makes a token
2. Screeching Scorchbeast — makes that many tokens
3. Glowing One — gains you 1 life
4. Mirelurk Queen — draws you 1 card
5. The Wise Mothman — puts a counter on a creature

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

a Room is fully unlocked — 28 cards in the game can cause this (Underwater Tunnel is one).

When Underwater Tunnel // Slimy Aquarium is fully unlocked:

1. Victor, Valgavoth's Seneschal — surveils
2. Ghostly Dancers — makes a token
3. Unwilling Vessel — puts a possession counter on itself
4. Gremlin Tamer — makes a token
5. Fear of Infinity — returns itself from the graveyard
6. Skullsnap Nuisance — surveils
7. Scrabbling Skullcrab — mills a card
8. Infernal Phantom — gets +2/+0
9. Entity Tracker — draws you 1 card
10. Fear of Sleep Paralysis — taps a creature

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

you surveil — 233 cards in the game can cause this (Underwater Tunnel is one).

When Underwater Tunnel // Slimy Aquarium surveils:

1. Mirko, Obsessive Theorist — puts a +1/+1 counter on itself
2. Prudent Fateseer // Peer Review — gives +1/+0
3. Diviner of Victory // Unwind History — gets +1/+1
4. Saheeli, Consul of Oversight — makes a token
5. Copy Catchers — makes a token
6. Proft, Consulting Detective — puts a +1/+1 counter on itself
7. Matoya, Archon Elder — draws you 1 card
8. Denzilore Fatehold — puts a counter on a creature
9. Whispering Snitch — deals 1 damage
10. Blood Operative — makes you lose life

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

a creature goes to a graveyard — 3,011 cards in the game can cause this (Underwater Tunnel is one).

When a card hits the graveyard thanks to Underwater Tunnel // Slimy Aquarium:

1. Syr Konrad, the Grim — deals 1 damage
2. Robot Domination — draws you 1 card
3. Voracious Brood — puts that many +1/+1 counters on itself
4. Dennick, Pious Apprentice // Dennick, Pious Apparition — triggers
5. Soulcipher Board // Cipherbound Spirit — triggers
6. Sefris of the Hidden Ways — triggers

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

an enchantment is cast — 3,673 cards in the game can cause this (Underwater Tunnel is one).

When Underwater Tunnel // Slimy Aquarium 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 (Underwater Tunnel is one).

1. Historian's Boon — When Underwater Tunnel // Slimy Aquarium enters, Historian's Boon makes a token

an enchantment enters the battlefield — 3,743 cards in the game can cause this (Underwater Tunnel is one).

When Underwater Tunnel // Slimy Aquarium enters:

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

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

anything gets a counter — 4,415 cards in the game can cause this (Underwater Tunnel is one).

1. Lonis, Genetics Expert — When Lonis, Genetics Expert gets a counter thanks to Underwater Tunnel // Slimy Aquarium, it triggers

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

a card in a graveyard — 7,589 cards in the game can cause this (Underwater Tunnel is one).

1. Sidequest: Card Collection // Magicked Card — Underwater Tunnel // Slimy Aquarium fills your graveyard toward the 8 or more cards Sidequest: Card Collection // Magicked Card needs

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

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

1. Colossal Grave-Reaver — When Colossal Grave-Reaver enters thanks to Underwater Tunnel // Slimy Aquarium, it mills a card
2. Unshakable Tail — When Unshakable Tail enters thanks to Underwater Tunnel // Slimy Aquarium, it surveils
3. Dreadhound — When Dreadhound enters thanks to Underwater Tunnel // Slimy Aquarium, it mills a card
4. Airbender Ascension — When a creature enters thanks to Underwater Tunnel // Slimy Aquarium, Airbender Ascension puts a quest counter on itself

362 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 (Underwater Tunnel is one).

1. Sidisi, Brood Tyrant — When Sidisi, Brood Tyrant enters thanks to Underwater Tunnel // Slimy Aquarium, it mills a card
2. Caradora, Heart of Alacria — When Caradora, Heart of Alacria enters thanks to Underwater Tunnel // Slimy Aquarium, it searches a library

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