Card

Platinum Angel

Mana cost {7}

Flying You can't lose the game and your opponents can't win the game.

Part of 103 known combos, 2 of them two-card. 5 official rulings.

Bracket

B1 Exhibition — Not in the same deck as its two-card combo partners: Ad Nauseam, Transcendence
B2 Core — Not in the same deck as its two-card combo partners: Ad Nauseam, Transcendence
B3 Upgraded — Not in the same deck as its early two-card combo partners: Ad Nauseam, Transcendence
B4 Optimized — allowed: No restriction beyond the banned list
B5 cEDH — allowed: No restriction beyond the banned list

Two-card combo with Ad Nauseam, Transcendence (early with Ad Nauseam, Transcendence)

Bracket: Lotus Vault analysis, with Commander Spellbook flags

103 known combos, 2 of them two-card.

Ad Nauseam + Platinum Angel
Produces: Infinite card draw
View on Commander Spellbook
Mister Negative + Wall of Blood + Platinum Angel
Produces: Near-infinite lifeloss for target opponent, Target opponent loses the game
View on Commander Spellbook
Platinum Angel + Axis of Mortality + Wall of Blood
Produces: Target player loses the game on each of your turns
View on Commander Spellbook

2009-10-01 · Wizards of the Coast
If you control Platinum Angel in a Two-Headed Giant game, your team can't lose the game and the opposing team can't win the game.
2009-10-01 · Wizards of the Coast
No game effect can cause you to lose the game or cause any opponent to win the game while you control Platinum Angel. It doesn't matter whether you have 0 or less life, you're forced to draw a card while your library is empty, you have ten or more poison counters, you're dealt combat damage by Phage the Untouchable, your opponent has Mortal Combat with twenty or more creature cards in their graveyard, or so on. You keep playing.
2009-10-01 · Wizards of the Coast
Other circumstances can still cause you to lose the game, however. You will lose a game if you concede, if you're penalized with a Game Loss or a Match Loss during a sanctioned tournament due to a DCI rules infraction, or if your _Magic Online_(R) game clock runs out of time.
2004-12-01 · Wizards of the Coast
You can concede a game while Platinum Angel on the battlefield. A concession causes you to leave the game, which then causes you to lose the game (Once you concede, you no longer control a Platinum Angel, so its ability can't prevent you from losing the game).
2004-12-01 · Wizards of the Coast
Effects that say the game is a draw, such as the _Legends_(TM) card Divine Intervention, are not affected by Platinum Angel. They'll still work.

Rulings: Scryfall · Wizards of the Coast