Nyaricus said:The first three, in a variety of ways.
"Anything goes, and anythign by WotC for sure - although there are some case-by-case diapprovals." Generally, this is followed by "... so long as I own it, or have had enough time to study it."
Arkhandus said:There are many 3rd-party books though that I'll just ban outright if the player intends to use them (I've seen more 3rd-party books used to break games than I have WotC materials; Mongoose's spellbook-thingy, I'm lookin' at you...).