Will there be a 2nd form of upkeep in form of Mana or something like that for spells too in Dom 3 ?
Then the issue could be solved imo by making "permanent" spells which give this way "enchanted" troop 50% resistence but cost upkeep each turn .
E.g. a spell for lightning resistence which costs 1 airgem per creature to cast + 1 Mana as Upkeep each turn and gives the troop 50% lightning resistence .
Mana is then e.g. 5 per Province + 5xNumber of Gems gained from sites/turn + 1 per 1000 Population if you have a magically skilled nation like Ermor etc. .
I would wish some more possibilities to enchance troops like Tuidjy as well because i agree with him .
In current Dominions you can outfit all your leaders very well and prepare them well for most situations with the right equipment but with your troops you can only do battlefield buffs which are expensive and not good enough .
So you just try to get the really good troops as quick as possible which are mainly the 200+ hp beasts like abominations , then Mech men and finally the really cheap creatures which are still very powerful , mainly vampires from Vampire lords + devils from soul contracts .
After turn 50 if you see troops you will only see troops from the above mentioned types which are about 10 out of about 500 possible troops .
So a system with permanent ritual like buffs for troops in Dom 3 would be imo a good idea . This is quite well done in Aow 2 SM already (one of the few things where it is a bit superior to Dom 2

) .
A 2nd form of magical upkeep for all summons would also reduce the extremely exponential growth in lategame a lot because you would have to household with your resources a bit more and wouldn't be able to do things like summoning 30 new Vampire lords from turn 70 or 80 on each turn .