Overpowered abilities, attacks, moves, perks, etc. that have made a game too easy

[The Fury]

From more recent, in Dragon Age Inquisition the archer's Hail of Arrows ability made it very easy to beat any enemy. I think I put the game on the hardest difficulty and still took down level 23 dragons at level 18.

This said, it glitched the game loads too if you spammed it. They've probably updated the game since and made it so you can't exploit it this way anymore.