Jungle Nasus
Flare mode. Your team just needs to know to save itself. Then you hit that 20 minutes mark and suddenly its 20 stacks of flare, 250 stacks of Q, a super tank, and no where to go but the lanes. And things start dieing. ^^ 15 works too, and its not as long as you think. Nasus does need to know to make its presence know in one way or another, but by 20 minutes it should be a super tank/god.
As far as I can see anyway. Just finished a game with roughly ~60 stacks of flare and ~550 stacks of Q...but they did have an afk...