Damage

"Damage" (ダメージ Damēji) is the primary way of reduce the player's life. It is dealt either by an attack, or by an effect that explicitly say "take/deal damage".

If the damage dealt is reduced to 0, or it becomes 0, it no longer considered as "being dealt damage".

Paying certain amount of life is not considered as "being dealt damage", so cards like Dragon Arms, Dragokeeper cannot reduce it.