Its very presence rips old wounds open to bleed anew.

Bloodletter of Aclazotz

Flying
If an opponent would lose life during your turn, they lose twice that much life instead. (Damage causes loss of life.)

The Lost Caverns of Ixalan

Flying
If an opponent would lose life during your turn, they lose twice that much life instead.

The Lost Caverns of Ixalan Promos

Bloodletter of Aclazotz's last ability doesn't change the amount of damage dealt to opponents. For example, if a 1/1 creature with lifelink deals combat damage to an opponent on your turn, they would lose 2 life, but you'd still gain only 1 life.