What it does
Bloodthirst is a static ability on creature spells that gives the creature extra +1/+1 counters if an opponent was dealt damage earlier in the turn. "Bloodthirst N" means it enters with N +1/+1 counters if the condition is met. For example, a 2/2 with Bloodthirst 2 enters as a 4/4 if any opponent took damage this turn.
The most common misunderstanding: it doesn't matter how the damage happened—combat, burn spells, even a Bloodthirst creature you already cast. It just needs to be damage to an opponent, not yourself, and it must occur before the bloodthirst creature enters. The counters are added as it enters, not after.
In Commander, the multiplayer format makes Bloodthirst easier to enable since you have multiple opponents to poke. Cheap evasive creatures or early aggression reliably turn these on, though Bloodthirst sees limited play overall.













