Trolls seem to be similar to D&D trolls. There are several subspecies, but all of them are large 3-meter tall humanoids with tough leathery skin and supernatural regenerative abilities so strong they are able to reattach severed limbs simply by holding them to the matching stump for a few moments. The most numerous and famous subspecies was the forest troll, which had vivid green skin and roamed throughout the great forested expanse in the north. They are very primitive and don't posses advanced metalworking ability. You need acid or fire to do permanent damage to them.
War trolls, armed with advanced metal weapons beyond their abilities to craft and protected by spells like a mind shield to deal with the Aranea are used by the invaders to attack Cyoria. Zorian met one advanced troll with some sort of sonic attack and massive resistance to magic.