You have to become a high level character in order for them to appear, or you can make them yourself in the arcane university.
go to all the mages guild halls and look for people that sell them
anywhere that sells spells,or mages guild members.
30 second invisibility
There's a student who walks around in the collage of Winterhold. He specializes in illusion spells, and can train you, and sell you illusion spells.
Cast spells
You can increase Intelligence permanently by the Intense Training perk, or by getting the Intelligence implant at the New Vegas Medical Centre. You can increase it temporarily by consuming Mentats.
Cast a lot of alteration spells.
You will always have a spell in use on Oblivion. If you don't want to use that spell, then simply select a different one. :)
conjuration, destruction, alteration, illusion, mysticism.
Destruction, Illusion, Conjuration, Restoration, Mysticism, and Alteration.
You cannot construct your own spells as you could in oblivion, you must find or purchase spell tomes and consume them.
The dark elf is very good for spells.
Ultimate Book of Spells - 2001 Veil of Illusion 1-18 was released on: USA: 10 February 2002
It should be in the list of all your other spells. Cast it normally.