User blog comment:Lykrast/Runes: why I hate them/@comment-16737371-20140326150842/@comment-4022742-20140326172911

Indeed, magic penetration does nothing for AP jungle champions unless they gank a lot. On the other hand, armor penetration has use for the jungle camps AND ganks, this is why AD champions have the advantage early game, and AP jungle champions usually have a strong team fight.

Hybrid jungle champions are just cheat though, looking at you, &.