Akrenu, the One with Venom

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
{5}{g}{g}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
As long as Akrenu, the One with Venom is monstrous, it has poisonous 3. (Whenever it deals combat damage to a player, that player gets three poison counters. A player with ten or more poison counters loses the game.)