What character type are you, and what level?
Rush Attack if you are a warrior and get him switched to melee combat. For a mage or ranger you can jump past him and hide behind the blood alter, coming out just long enough to attack.
You could also leave the temple and level up elsewhere, then return to fight him.


How to defeat Amdusias?

Amdusias

Killing Amdusias! >.<


Welcome to the forum. wave