The resist spell is avaliable too all guilds that have -any- spells. You first must kill Astillar the Blue Dragon, in the wastelands. In the wastelands, you cannot use any spells, or healing, ONLY specials. I recommend getting a fighter to kill him for you. He carries an Amber which is worth 50pc in any shop, and an Endless Spell Components Bag (ESC) and a Key. This key is for the room southeast of him,
the resist room you enter there and i believe drink water, to gain the spell If you are a fighter or such that cannot use the spell, you can still get it, to get the quest point, but can't cast it.
From East Gate Kildareh:
5e,ne,2se,2e,ne,e,sw,2s,2nw,w,sw,nw,w,d,e,s (Astillar is here and autos, kinda hard, you cannot use spells.)
Get the key off the corpse,se,drink water
Reverse dirs to get out.