Destruction/Fire

[Hoverdog]

Tier 1: Flame Arrow (T, Instant, direct fire damage), Immolate (T, Instant, small damage to all units)
Tier 2: Arson (S, Instant, destroys a random building), Minefield (T, Instant, places a few explosive mines on the battlefield)
Tier 3: Fireball (T, Instant, fire AoE damage)
Tier 4: Fire Storm (S, Instant, fire damage)
Tier 5: Flame Strike (T, Instant, large direct fire damage)
Tier 6: Doom Bolt (T, Instant, irresistible damage)
Tier 7: Incinerating Cloud (T, Instant, large AoE, large damage)
Tier 8: Meteor Storm (S, Global Enchantment, continuous damage and chances to destroy buildings)

[Troy_Costisick]

Arson is way too low level. Putting that little amount of mana and casting time into a spell in order to destroy something that can take 10-20 turns to build is ridiculous. Spells on levels 3-7 all look like the same thing.

[Hoverdog]

Arson might cost a bit, plus it's completely random and its power diminishes in the long run.

Spells 3-7: 3rd is AoE, 4th is Strategic, 5th is single-target, 6th is Doom Bolt (irresistible, constant damage), 7th is large AoE. We might add some additional penalties to one or two to further distinguish them.

[Happerry]

Personally I'd swap Fireball and Arson.

[ampoliros]

Something to think about...
Immolate is nothing like the Immolation spell in MoM. The difference might upset some players.
MoM Immolation was a touch attack that did a 4 strength fire attack to all figures in target unit.

[Happerry]

Could always rename it Heat Wave.