Very simply increased his own combat power.
As a hero, his damage resistance is very strong. If he becomes uncontrollable, his melee output is off the charts, restoring his own health while slashing enemies.
He's practically a battlefield bulldozer charging headfirst.
When he leads the charge, he can sturdily stand at the forefront of the battle line, dealing fierce damage and shattering the enemy's elite phalanx.
Sending cannon fodder against him is almost ineffective.
Sending elites against him might end up being costly.
In a battle between equals, no matter how you choose, it's quite difficult.
