I like how you can make the flame rat explode, i think more enemies should have a mean of becoming useful to the player if the same is skilled enough, so here is some sugestions for features to existing enemies to have that also.
Blightstormer
I hate them with passion however, i’d like if there was a point in his magical charging where a destructible spot would blink for 2 seconds before turning into a vortex where if the player shoot that a small series of chain lightnings would stun/stagger all enemies close to that area.
This would make for when hes sniping people from unreachable distances.
Leech
Shooting his staff before he grabs a player could shatter it to pieces resulting in him just running away barehanded instead, make him run away on foot and throw rocks at players whenever hes not alone anymore, that doesn’t make him as useful as other examples but that be funny anyway.
Bestigor
Interrupting his charge could make his fall drop/stagger everyone in its path, something similar already happen if you dodge him, but it could be stronger, hes a big boy, the area should be larger.
Globadeer
Now this one should be extremely difficult to achieve, when his orb is about to hit the player, a skilled enough player could grab it in the air by hitting E and now they have a gas granade, again the window to pull this off should be very tight, making it hard for player to just use them as grenade dispensers, and the gas still hurts the player so caution should be required.
Make its damage similar to a hagbane hit, but one that lasts as long as the gas stays there.
Chaos Warrior
Love them to death, i kind wish there were more variations of them, but my sugestion for him is to make it possible for shield baring characters to parry his attack by shield bashing it right when its about to connect sending his axe at high speed towards the direction of the shield impact thus killing enemies in its path, a weaponless chaos warrior could still kick and it would try to retrieve his axe if its in a playable area, otherwise he would just attempt to kick you off the ledge.
I just like when theres more to enemies than merely walk to player / try to kill player, specially nowdays that coop shooters are starting to appear out of nowhere, everyone is out to get your cheese fatshork, but thanks to the team talent and hard work you are ahead and you should stay ahead.
Keep up the good work.