text: Knollspine Dragon's ability checks only whether damage was dealt. It doesn't care whether the player's life total also changed for other reasons (such as if the player paid life or gained life). For example, if an opponent was dealt 4 damage and gained 6 life during the turn, that player will have a higher life total than they started the turn with — but Knollspine Dragon's ability will let you discard your hand and draw four cards.