It seems to me that most magical spells would fall under only a few types. Most games published today dress them up and modify them slightly so that the druid can summon better while the wizard can throw a better fireball. Stuff like that. I am taking a different rout by using broad spell types. You can then add opposites to double the number of spells. A caster will have a set number of points per battle to cast spells. Each spell will have a casting cost. Spells will be assigned to caster types. I might even add some sort of passive effect for each caster. Here are some of the spells I’ve come up with so far.
Haste: Allows the target unit to move D6″. A’6′ doubles the unit’s movement. 1 turn duration. Cost 2 points.
Slow: Deducts D6″ from the target unit’s move. A ‘6’ reduces the unit’s move to 0. 1 turn duration. Cost 2 points.
Summon: Summons a monster to do as the caster bids. A ‘6’ summons a large monster. Permanent until dispelled. 3 points.
Banish: Destroys a summoned creature if the caster can beat the opponent’s die roll. A ‘6’ makes it automatic. Immediate effect.
Protect: Increases the target unit’s protection by 1 class. A ‘6’ makes the unit have the best armor in the game regardless of matchup. Permanent until dispelled. 2 points
Negate: Decreases the target unit’s armor by 1. A ‘6’ gives the unit the worst armor in the game regardless of matchup. Permanent until dispelled. 2 points
Strength: Increases the target unit’s combat skill by 1. A ‘6’ gives the unit the best combat skill in the game regardless of matchup. Permanent until dispelled. 2 points
Enfeeble: Decreases the target unit’s combat skill by 1. A ‘6’ gives the target unit the worst combat skill in the game regardless of matchup. Permanent until dispelled. 2 Points
Missile attack (Fireball Lightning etc): 1+ 1D6 per point put into the attack. A ‘6’ doubles the effect of the points put into the fireball. Ex. 2 points would be a 3 die fireball. A ‘6’ effect would be a 5 die fireball. Note that a caster may always throw a 1 die missile attack at no cost. Instantaneous. 0-3 points
Missile shield: Makes the target unit fully armored against normal missiles. A ‘6’ makes the unit invulnerable to all missiles including magical ones. 1 turn. 1 point.
So that’s 10 spells right there. I can probably come up with a few more. A caster can not have more than 1 of each type of spell going at a time. They could summon a creature, strengthen a unit and cast a fireball for instance. Magic points can be variable but I suspect 10 points is a good number. Perhaps just 1 caster per army would be enough magic for a battle.