应该由起始玩家结算。玩家不控制爪牙，也不控制反派。爪牙攻击反派，翻出的增效属于没有指定玩家的效果，所以应由起始玩家结算。
在FIRST PLAYER规则中有：
If an encounter card requires a card ability to be resolved, a game function to be performed, or a choice to be made but does not specify which player should act, the first player does so.