So each class (to my knowledge has a counter to Deva) I think the issue is more than Deva has started droping before the other classes potentially get their counter skills/levels high enough to counter it.
Don't take any of this as biblical as I am not currently in Chronicles HQ to confirm, but:
Warriors - Have Shoulder dash (which will only work so well if deva is set to follow), and Entrapment should work on Deva paralyzing it (granted I ported entrapment straight out of official code, so it is limited to 800x600 resolution atm, but when BH reboots next this will be fixed).
Assassins - Have SwiftFeet which has started dropping, which tbh is the best counter as there will be no walk after flinch, this + ShadowStep will keep a taoist on his toes (and keeping a tao on his toes is a fantastic achievement in my opinion as they have always dominated pvp in my eyes).
Wizards - Wizards have elec shock (although I am not sure if this will stop deva from attacking, might make it stop following) and eventually their mirroring will have the same commands as Deva (apologies this is taking longer than expected to get in)... In addition 2.0 should see the arrival of a new high level pet for wizards.
Archers - I feel like archers get to short straw a little as their counter is a bit sucky, however, Decoy might distract deva for a couple of seconds whilst your able to get a arrow barrage off, this + AttunedBody (coming in 2.0) should keep you steady in pvp against a tao.
Deva (in my opinion) has always been a game changer for taoists and pvp, I will have a look at it not missing as all mobs/skills should have a chance to miss depending on your magic resistance.
My ten pence
Sam