adisplayofcharacter replied to your post: If I give my opponent’s Infinite / Infinite Bramblesnap Spiritualize (whenever it deals damage, I gain that much life) am I dead when it hits, or do I come out at infinite life?(disregarding the fact that you can’t do actual infinities, it’s just to convey the point)

How would one lose before Spiritualize ever hits the stack? If he cast it during Declare Blockers, it would resolve before combat damage is dealt.

Spirtualize is a triggered effect. The creature needs to deal damage, then Spirtualize has the effect go on the stack. That’s what trigger effects do. But before the effect can resolve, the game sees a dead player, and they lose the game with Spirtualize on the stack (which then also gets removed from the game since the player who owns it just lost the game).

603.1. Triggered abilities have a trigger condition and an effect. They are written as “[Trigger condition], [effect],” and begin with the word “when,” “whenever,” or “at.” They can also be expressed as “[When/Whenever/At] [trigger event], [effect].”

603.2. Whenever a game event or game state matches a triggered ability’s trigger event, that ability automatically triggers. The ability doesn’t do anything at this point.

603.3. Once an ability has triggered, its controller puts it on the stack as an object that’s not a card the next time a player would receive priority. See rule 116, “Timing and Priority.” The ability becomes the topmost object on the stack. It has the text of the ability that created it, and no other characteristics. It remains on the stack until it’s countered, it resolves, a rule causes it to be removed from the stack, or an effect moves it elsewhere.

….

704.1. State-based actions are game actions that happen automatically whenever certain conditions (listed below) are met. State-based actions don’t use the stack.

704.3. Whenever a player would get priority (see rule 116, “Timing and Priority”), the game checks for any of the listed conditions for state-based actions, then performs all applicable state-based actions simultaneously as a single event[…]

704.5a If a player has 0 or less life, he or she loses the game.