Evil Exception says "Regardless of alignment or class restrictions, a hellbred can cast spells with the evil descriptor and never gains negative levels while welding evil magic items, such as unholy weapons or
demon armor. This ability does not shield a hellbred from from losing access to class features if he violates a class's code of conduct. For example, using a
+1 unholy longsword to slay orcs would not violate a hellbred paladin's code of conduct, though using the weapon to kill another paladin would."
Nowhere does it say you're immune to the effects of evil spells you or anyone else cast.
I always expected someone to half read it and claim something like
lol omg I'm awesome. Check this out guys
"a hellbred can cast spells with the evil descriptor and never gains negative levels while welding evil magic items"
Grab an unholy weapon and you're immune to negative levels. leet haxxors rolf rolf roflmao.
Pelor knows theres enough people running around on here that would if they ever stopped to actually read the books to find it rather than reading umm, whatever the 339 is calling it's self this days.