[Faceman]

Tolgerias can be beaten with standard anti-mage tactics:
1.) Try to hit him with every wand and fast spell you have available
BEFORE he builds up his defenses (Mages don't have a lot of hp)
2.) Memorize some Breach or SpellThrust
3.) Try out Miscast Magic on him
4.) Try to whack him with a tool that does extra damage (i.e. Flail of Ages, Flame tongue, Hammer of the Thunderbolts, Gesen Bow - You probably have one of them - not the Gesen I think)
5.) walk in sight - walk out of sight and wait for protections to wear off
6.) Use the Ring of the Ram

And yes Tolgerias is the Wizard you were supposed to meet. He would have send you after Valgyar as a bounty hunter to procure his body
so he could enter the sphere.