I am about 2/3 through the Impossible Mage game. Now I consistently pull off 0-loss battles thanks to the following spells:
(1) Resurrection. Obviously needed for 0-loss. Inquisitor + Gift gets better at end game (when your stack of inquisitors grows over your spell power).
(2) Trap. Very effective at stopping an advancing army. Also you... just know where that huge dragon stack is going to land, right?
(3) Mass Lv 3 Magic Shackles. Remove annoying fireballs from all demons!
(4) Sheep. Instantly render a huge stack useless for 2 terms. Better than slow the stack does not retaliate - so you can freely gang up and beat the crap out of it.
(5) Slow. Cast it early on a bad stack and don't worry about this stack for quite a while.
Direct damage spells are losing their appeal. You can still fireball out a huge Royal Thorn stack as there is 100% damage bonus.
Other very handy things:
- Reaper's Time Back - take heavy loss and boom! It never happened! Be careful that the old location has to be kept empty.
- Higher magic. I only have level 2 and it is soooo good.