They often appear along with other Lizards. These creatures attack with melee attacks only, and aren't very fast; thus, an easy kill for paladins and mages. Even though it has a huge amount of hitpoints. Its attacks are rather weak, so they won't be a problem for experienced knights either.
Mages and Paladins: Run away from them while shooting runes or bolts; be careful while running, or you will run into another respawn. Knights: If you are skilled enough, the templar shouldn't be much of a problem. Just attack it, and be careful so you don't get surrounded. Level 55 with skills 70/70 and it should be easy with decent equipment.