I find myself always defaulting to using the same one or two powers. So I made new ones. 
Additonally theres also a few more powerful versions of vanilla spells. 
They cost a lot to cast, but pack quite a punch. Suited for a stealth mage playstyle. 

You can find the Tomes in the arcanum.
I recommend getting a magic scaling mod if you want these to scale better.


Spells:
(all casting costs are set to automaticly scale)

Strong Firebolt: Deals 75dmg
Extreme Firebolt: Deals 200dmg
Hellfirebolt, Hell Ice Spear and Hellthunderbolt: Deal 500dmg


Powers:
(all powers are lesser powers and have the standart 3 second cooldown)

Bound Bow: Summon a Bound Bow for 10 seconds
Calm: Pacifies target up to level 9 for 5 seconds
Fear: Fear a target up to level 9 for 2 seconds
Fury: Enrage a target up to level 6 for 15 seconds
Fast Healing: Heal 15

Firebolt: Deals 11dmg
Ice Storm: deals 6dmg
Lightning Bolt: deals 13dmg
Fire Rune, Frost Rune and Lightning Rune: deal 25dmg

Invisibility: Turn invisible for 2 seconds
Muffle: Silence your movement for 15 seconds
Stoneflesh: Increase your armor by 30 for 15 seconds
Vanish: Become Ethereal for 2 seconds

Perfect Block: Increase dmg blocked by 50% for 6 seconds
Quick Shot: Archery deals 50% more dmg for 2 seconds
Silent Step: Increase sneak by 50 for 6 seconds
Strong Arm: One Handed attacks deal 50% more dmg for 6 secons
Heavy Hit: Two Handed attacks deal 50% more dmg for 6 seconds