The most powerful warrior.

The cooldown still needs to be activated next to the enemy stack (imagine the cooldown under Berserk... it will decimate its own units, whoa), and the Elves, with their in-fight ability at the very beginning of the battle, will noticeably damage the enemy stacks... They are also very tactically effective: for example, you can place them in front of the riders (in a battle against the Tribes of the East) so that they don't scatter, or in front of the paladins (in a battle against Haven).

Added after 3 minutes
P.S. I'm not saying who would win in a one-on-one fight; I'm talking about their usefulness in an army...