Valgavoth's Lair

a land enters the battlefield — 1,560 cards in the game can cause this (Valgavoth's Lair is one).

When Valgavoth's Lair enters:

1. Primeval Bounty — gains you 3 life
2. Toph, Earthbending Master — puts a counter on a permanent
3. Dancing from Dark to Dawn — makes a token
4. Emeria Shepherd — brings a card back
5. Quest for the Necropolis — puts a quest counter on itself
6. Soul Stair Expedition — puts a quest counter on itself
7. Nissa of Shadowed Boughs — puts counters on a permanent
8. Thranduil, Sindarin Liege // Silvan Rally — makes a token
9. Silvan Reveler — returns itself from the graveyard
10. Floral Evoker — puts a +1/+1 counter on itself

199 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 (Valgavoth's Lair is one).

1. Historian's Boon — When Valgavoth's Lair enters, Historian's Boon makes a token

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

When Valgavoth's Lair 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

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