Dimension 4-> Levitate (grant flying promo to all units in the stack, essentially)
Sun 4 -> Scry (gain sentry I, II, and Perfect sight granted to caster upon first casting. Acts like a hawk with near unlimited range)
Water 4 -> Sea March (waterwalking for entire stack, or maybe just arcane and melee)
Law 4 -> Ordum Magnamitas, grants Magnanimitas promo which is removed upon combat. (Acts like loyalty, valor, and strong, exp gain stacks with valor and strength boost will occur even on a unit already having the actual strong promo, cause its a new promo)
Body 4 -> Flesh Hunger (grants cannibalism promo to all divine, melee, and recon units)
Chaos 4 -> Battle Frenzy (grants all non-hero melee units drill I-III and burning blood promo, as well as random promotions of all kinds. All the way from Plague and Weak to Strong, Valor, or enchanted blade ... maybe even a chance at magnanimitas?)
Entropy 4 -> dissolve (can be resisted, grants enemy units the weak promo, the withered promo, and removes ALL metals, including mithril)
Demon + Entropy 4-> Corrupt (can alternatively turn a 16 tile block into hell terrain)
Shadow 4 -> Fade Out (grants invisibility to all arcane units, hidden to all other units)
Wind 4 -> Hurricane March (grants all units, living or non, +1 movement and commando. Even Siege weapons)
Enchantment 4 -> Power Infusion (grants heavy and combat 1 to all golem and seige units)
Fire 4 -> Asteroid (casts ring of Fire while summoning 3 or 4 asteroids. Asteroids are like meteors, only they have +1 fire affinity, and double the bombard value, and three times the collateral damage amount, still to a limited max of course, in collateral that is)
// alternatively, Fire4 could be the old Meteor shower, which summoned 3 meteors
Force 4 -> Banish (can be resisted. Enemy undead, demons, and angels, have a chance to dissapear back from whence they came)
Death 4 -> Exterminate (range 2, cannot be resisted, reduces enemy city to pop 1, creates a wraith for every pop the city had. Can also target a stack, giving a 10% chance for each living unit to turn undead, and a 5% chance for a living unit to die. Effects units in targeted cities. Always attacks a rival city if its within range, otherwise goes for largest stack)
// alternatively you could make the spell simpler by reducing city pop to 1 and creating a blight in the city
Ice 4-> New Winter (turns all tiles to ice in a 16 tile block. Permanent transformation. (countered by below)
Nature 4 -> New Summer (works like genises on a 16 tile block, centered on caster. also summons a Treant.)
Spirit 4 -> Spirit's Resolve (a 16 square sanctuary, as well as supplying demon slaying and undead slaying to all units in the stack.)
Metamagic 4 -> Omniscience (gain knowledge of entire map, can see rival tech progression (as if they were a vassal)
Life 4 -> Everlasting Devotion ->grants immortality promotion to melee units and recon units(and mounted?) (and Divine?) anything but arcane, basically. possibly can be used only once per supermage, or maybe Life 4 is lost upon casting it, requiring a further level to buy it again, in order to use it again.
Mind 4 -> Mind steal -> randomly steals enemy tech, has a chance (2 tile range) of converting enemy arcane units ... 5%. Another 5% to give enemy arcane units (3 tile range) the held promotion.
Earth 4 -> Kilmorph Provides -> creates random resource on a barren mine+hill
Creation 4-> radomly creates a food or animal resource, 5% of doing nothing, 5% of randomly creating a great person instead (except for great prophets)
I made these spells with the Opinion that each super mage (unless Patria) can only know ONE tier 4 spell