Oasis

damage is prevented — 568 cards in the game can cause this (Oasis is one).

When a creature has damage prevented thanks to Oasis:

1. Phyrexian Vindicator — deals that much damage
2. Selfless Squire — puts that many +1/+1 counters on itself
3. New Way Forward — deals that much damage
4. Samite Ministration — gains you that much life
5. Judgment of Alexander — deals its power damage

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

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

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