Well, well. I've got a lot of ideas for spells. So if you're making your map in the medieval age try to devide the characters into a few groups, thought whatever you'd choose it will be a zealot but with unique abilities.
So let'ts say there would be a wizard.
hp 100
$=1(1 upg=1$)
And a few spells:
-Mirror image(hallu)
-Lightning(psi)
-slow(ensnare)
-paralyze(mealstorm)
-etheral shield(defense matrix)
-drain(emp)
Per lvl up you'd get a new spell to choose.
A typical warrior(palladin for ex.)
hp 100
$=3
-heal
lvl 1- creates a medic with 0 nrj(so it heals just a little bit)
lvl 2 - creates a medic with 10 nrj
lvl 3 - creates a medic with 25
(for a specific time)
-The all seeing eye(creates an observer above the palladin, make all the units blind, so the map would see a bit bigger

)
-have no idea for a name(makes the palladin invi for 10 sec)
-Command - causes an enemy to freeze(statis)
Theif/rogue whatever.
hp 100
$=4
-the theif could hide in shadows using an arbiter with 0 dmg.
-horror - makes the enemy around the theif run away(junkyard script)
Try something like theese

.