Dungeon Delver

an enchantment is cast — 711 cards in Dungeon Delver's colors can cause this (Dungeon Delver is one).

When Dungeon Delver is cast:

1. Defiler of Dreams — draws you 1 card
2. Hermes, Overseer of Elpis — makes a token
3. The Fantasticar — turns something into a creature
4. Variable Chaser // Arc of Fortune — gets +1/+1
5. Shark Typhoon — makes a token
6. Lieutenant Commander Data — puts a +1/+1 counter on itself
7. Drake Hatcher — gets +1/+1
8. Machine Man, Model X-51 — puts a +1/+1 counter on itself
9. Traxos, Academy Guardian — gets +1/+1
10. The Vision — triggers

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

an enchantment enters the battlefield — 714 cards in Dungeon Delver's colors can cause this (Dungeon Delver is one).

When Dungeon Delver enters:

1. Thassa's Devourer — mills a card
2. Unwilling Vessel — puts a possession counter on itself
3. Shoal Kraken — draws you 1 card
4. Sage of Mysteries — mills a card
5. Scrabbling Skullcrab — mills a card
6. Entity Tracker — draws you 1 card
7. Protean Thaumaturge — copies a permanent
8. Fear of Sleep Paralysis — taps a creature
9. Whitewater Naiads — triggers
10. Stalked Researcher — triggers

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