4Hooves2Appendages wrote:Bolt of Magma does somewhat less than 67% of the damage Bolt of Fire does, its range is shorter and it’s less accurate.
That's actually not true, given that "fairly equally skilled in both earth and fire" bolt of magma will do something like 95% of the damage of bolt of fire. They scale the exact same way with spellpower (for to-hit and damage), bolt of magma has slightly more variance, and bolt of fire has a tiny tiny amount higher starting damage and to-hit bonus
It would be fairer to say "It takes 50% more XP to train 3 schools over 2 schools to the same level, to get the same exact spellpower out of both spells".
However somewhat counter-intuitively (because XP and spellpower both improve results in an ever-decreasing amount) a missing 33% of XP translates into a much much smaller amount of damage. (It takes less XP to train earth from 0->5 than fire from 20->25 and you get less spellpower benefit from spell schools the higher they already are, so going from an average of 10->15 has much more impact than going from 15->20)
The net result is that bolt of magma is somewhere between 75 and 90% as effective as bolt of fire against a single target given the same amount of XP investment. The missing range actually impacts BoM a lot when it comes to multiple targets, since you lose 2 range per monster hit, hitting a third creature with BoM is not nearly as likely as it is with BoF.
The *real* question you should ask yourself is "why would you ever use BoM against fire-resistant creatures, when you could just use a pure-earth spell instead" LRD and iron shot are both way way more effective at dealing with fire-resistant things than BoM could ever be (because BoM is partially resistable by things that resist fire spells)
If you actually have similar levels of fire and earth skills (for some reason) you should use non-fire spells to kill things that are immune to fire spells. BoM's true problem is that it has no role that's not fulfilled by other, better spells (BoF and fireball are better fire spells, iron shot and LRD are better to kill fire-immune stuff with) there's just no reason to memorize or cast this spell unless you literally have no better option, which you almost certainly will.