what jgs are good for teamfights?

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I've seen Amumu jungle as frequently as alistar and morgana Like never Which is weird

Mainly because he does DPS instead of burst damage that is heavily sought after in junglers. Since the game is so fast paced, his W doesn't deal as much damage as it should before something explodes (usually him). Plus, he needs to rely on a Q in order to combo into R.

Not that he isn't strong. Just simply that there are other better picks. That and his R's cooldown is disgustingly long when any other jungler can pop their ult way faster.