Viper the Pandemic

Deathtouch Lifelink Viper the Pandemic can only attack alone when viper deals combat damage to a player put eleven +1 +1
counters one target creature an opponent controls at the beginning of that players upkeep remove a +1 +1 counter from that creature when that creature has no more +1 +1 counters its controller loses the game (destroying the creature stops this effect)