I have started a game with a TOB created Fighter/mage/Thief character. I can only access the fighter and thief special abilities which really seems to be weird. Another thing is, i just finished the planar sphere quest and i read somwhere that a mage has special quests after the planar sphere but i dont know how to get it or if its another problem (i have also finished the mae'var quest and the de'arnise quest and am currently doing those quests now /fighter/thief/) So have i missed anything, can i annitiate the quest from the planar sphere or do i have to go somwhere to get it, or is 2 special quests the limit??? Im also really confused as to why i cannot get mage special abilities.
thanks for the help

You can have only one stronghold, so if you've taken Mae'var's guildhouse or De'arnise keep, you can't take Planar sphere anymore.

Mage high level abilities are mostly 10th-level spells, and fighter/mage/thieves can't cast 9th level spells, unless you're experience cap remover. Although, you should be able to choose extra 6th-level spell (and then 7th and 8th).

And you can't wear armor when casting spells.