I'm trying to recreate one of the old classes from Oblivoin, I've chosen the agent build.

Agent
Specialization: Stealth
Attributes: Agility, Personality
Skills: Acrobatics
Illusion
Marksman
Mercantile
Security
Sneak
Speechcraft

So, I've got sneak, speech, lockpicking, marksman and illusion but I've added blade and light armour too......but I've never played a mage type character so i don't really know skyrims magic at all , what kind of spells should i be using that are agent-ey?

Invisibilty and Muffle along with sneak make you undetectable.