I ran into one in the second spellhold asylum map (before the cat o' 9 lives room).  Why can't I get Breach to work on him?  Is it immune to 5th level spells or something?  I've fired 4 Ruby Rays at it and Breach still does nothing.   
Also, remember to bring Potions of Absorbtion with you to Spellhold.  They really help against the Amber golems.
 
