Card

Vito, Thorn of the Dusk Rose

Mana cost {2}{B}

Whenever you gain life, target opponent loses that much life. {3}{B}{B}: Creatures you control gain lifelink until end of turn.

Part of 28 known combos, 8 of them two-card. 5 official rulings.

Bracket

B1 Exhibition — Not in the same deck as its two-card combo partners: Exquisite Blood, Bloodthirsty Conqueror, Beacon of Immortality, Blood Tribute, Revival // Revenge, Shard of the Nightbringer, Enduring Angel // Angelic Enforcer, Volcano Hellion
B2 Core — Not in the same deck as its two-card combo partners: Exquisite Blood, Bloodthirsty Conqueror, Beacon of Immortality, Blood Tribute, Revival // Revenge, Shard of the Nightbringer, Enduring Angel // Angelic Enforcer, Volcano Hellion
B3 Upgraded — Not in the same deck as its early two-card combo partners: Exquisite Blood, Bloodthirsty Conqueror, Beacon of Immortality, Blood Tribute, Revival // Revenge, Enduring Angel // Angelic Enforcer
B4 Optimized — allowed: No restriction beyond the banned list
B5 cEDH — allowed: No restriction beyond the banned list

Two-card combo with Exquisite Blood, Bloodthirsty Conqueror, Beacon of Immortality, Blood Tribute, Revival // Revenge, Shard of the Nightbringer, Enduring Angel // Angelic Enforcer, Volcano Hellion (early with Exquisite Blood, Bloodthirsty Conqueror, Beacon of Immortality, Blood Tribute, Revival // Revenge, Enduring Angel // Angelic Enforcer)

Bracket: Lotus Vault analysis, with Commander Spellbook flags

28 known combos, 8 of them two-card.

Vito, Thorn of the Dusk Rose + Exquisite Blood
Produces: Infinite lifegain triggers, Infinite lifeloss, Infinite lifegain
View on Commander Spellbook
Vito, Thorn of the Dusk Rose + Bloodthirsty Conqueror
Produces: Infinite lifegain triggers, Infinite lifeloss, Infinite lifegain
View on Commander Spellbook
Vito, Thorn of the Dusk Rose + Beacon of Immortality
Produces: Near-infinite lifegain, Near-infinite lifeloss for target opponent
View on Commander Spellbook

2020-06-23 · Wizards of the Coast
In a Two-Headed Giant game, life gained by your teammate won't cause the ability to trigger, even though it caused your team's life total to increase.
2020-06-23 · Wizards of the Coast
If an ability triggers whenever an opponent loses life and causes you to gain life, such as the ability of Exquisite Blood, this will loop until either you win the game or a player takes an action to break the loop.
2020-06-23 · Wizards of the Coast
Because Vito's first ability doesn't deal damage, you won't gain life when it resolves if Vito has lifelink.
2020-06-23 · Wizards of the Coast
If you gain an amount of life "for each" of something, that life is gained as one event and Vito's first ability triggers only once.
2020-06-23 · Wizards of the Coast
Each creature with lifelink dealing combat damage causes a separate life-gaining event. For example, if two creatures you control with lifelink deal combat damage at the same time, Vito's first ability will trigger twice and you may choose a different opponent for each trigger. However, if a single creature you control with lifelink deals combat damage to multiple creatures, players, and/or planeswalkers at the same time (perhaps because it has trample or was blocked by more than one creature), the ability will trigger only once.

Rulings: Scryfall · Wizards of the Coast