[Crevan]

Buffs useful only on high levels: spend lot of money for weak buffer...only if you have no choice - weak Mictlans, small armies of Niefel, sacred but damn weak White Centaurs and other
Fire...I think, some rods in hands of your commanders looks better. They don`t require upkeep, can`t be cursed/diseased/killed - but delivers really good damage
Spam of skeletons - you think it`s good idea? In VERY early game may be, then flying units or archers can easily take down your "spammers" before they can change situation on battlefield
All mages become useful only when you research powerful combat spells. It takes time, right? Even with "Very easy research" and nation with powerful researchers it takes about 30-40 turns before you gain access to 5+ level spells in Alt/Evo/Thaum. I better research Conj/Const line with summons and artefacts - it will add me more power, than mages