Enduring Angel // Angelic Enforcer and Defiant Bloodlord on the battlefield (Enduring Angel // Angelic Enforcer as Angelic Enforcer.).
Angelic Enforcer does not have summoning sickness.
Your life total is higher than or equal to an opponent's.
Steps
Declare Angelic Enforcer as an attacker.
Angelic Enforcer triggers, doubling your life total.
Defiant Bloodlord triggers, causing target opponent whose life total is less than or equal to Angelic Enforcer's power to lose life equal to the life you gained.
That opponent loses the game due to having 0 or less life.