Just some pointers.
1) Free Action is not a short-duration spell, and actually lasts quite long.
2) Dispel Magic is available early in the game. Prevention is still better than cure, but at least you have an early cure.
3) You forgot to mention Lilarcor +3
4) Imprisonment can be countered by all classes in the game. That is what the Protection from Magic/Undead scrolls are for. Berserkers have their enrage. Clerics have the Shield of Archons.
It is
not only the Mage who can counter Imprisonment.
5) Time Stop
is extremely powerful, but to get it legitimately, you need ToB. The SoA Xp cap prevents you from attaining it in SoA, short of scrolls. When you proceed to ToB, you will be thankful for Time Stop.