Tree of Perdition by tapping it, causing its toughness to become equal to an opponents life total, and causing that opponent to lose life equal to the difference between their life total and
Tree of Perdition's toughness as the ability resolved.
At the beginning of your end step, [[Doubler - LIfeloss]] triggers, causing the opponent to lose life equal to the life they lost this turn.
Notes
If the opponent's life total was at least double
Tree of Perdition's toughness as the ability resolved, they will lose the game as a state-based action due to having 0 or less life.