My bad.
So that trade language is in SpC, and supercedes.
Awesome. Call it: Incentive to Play a Warmage.
The preceding text claims that the rules applicable to similiar classes. This means the rules applies on the same basis (requires DM cooperation, despite it not being advised) to two things:
1) Warmages, even if you claim it's not the same class listed.
2) Dread Necros and Beguilers.
Also, familiars are really good, so it balances it out. Take Obtain Familiar to become uberz.