I do agree it would be cool if enemy had monsters instead of tanks. I mean they can have the same stats and 5 categories as our tanks, just make them reskinned as monster.
Each of them could have 3 different color variants, since there are many active abilities, and the player recognize the tanks and what abilities they can pull of once enough fights have been fought, this would be the same. Like I dunno a Purple monster shots a 200% dmg 100% accuracy shell, A blue one has the +Defense, DMG -Mspeed ability, yellow can turn on Speed, Red has stun, etc.
Pretty much just a color indicator so that players can learn the metagame same as how they learn to recognize the current tanks.
As for the wraiths themselves. If they would be a normal spawn they would have to be nerfed. One taking 4-6 tanks due to the scaling issues the game has would be to brutal for normal maps, and would render Grinding which this game requires a lot extremely stupid.
I think the enemy scaling to your general lvl is very bad mechanic and needs to be re-done. Our tanks lvl so slowly - especially 5* - that if you ever swap in a new one, you are crippling yourself horribly. The maps need to have the difficulty fixed, increasing in lvl as you progress through, not taking into account your General.
This and the multiple copies of the same tank limit. SU and Mouse spam is super retarded, but getting 5 Catrionas one after the other, all activating their abilities and pretty much shooting down anything before it gets close enough is no fun either.
Limit of 2 of the same tank per map shouldnt be that bad. If we can do with building our teams from all those tanks, and running a fully working team I dont see why AI couldnt generate it in a similar fashion as well rather than spaming 4-5 very powerful tanks over and over again.