When facing them, it is best to take them out before they can enter melee. Use them to counter other strong melee units. Some also have melee-focused skills like Charge Defence. Fire is known to harm this healing process, so be warned that flaming attacks will cause more damage to units with Regeneration. They are often heavier and attack at a slower rate though, making them less efficient against poorly-armoured targets. Blessed by the Chaos Gods with intelligence, he has vowed to rise up and lead his race to dominance, killing and eating his enemies along the way.
Throgg, aka the Troll King, is a most unusual troll.