Please devs, you can Fix Mana Regen Bug/Infinite CHs which is simple, double check Mana Before Cast and After Cast.
Actual system:
You click Spell
Check Mana
If Mana
Starts Casting
Else
You have no Mana
Once Spell is finished casting regardless of your Mana the spell just lands, if you add a double cast for the NPC, players can actually stops CHs and Gates with Mana Sieves/Drain, because even tho mobs casts once rechecks that he has no mana it will be interrupted.
Thats actually exploitable from players to rebuff for 0 mana after a ress. Like to stand on the ress spot, start casting and before the end of cast just accept your ress box so your oom with rezz effect and then once the cast timer finish you will end up with C2 Grp in your grp with 0 mana, or Aego on tank/Self using 0 mana.
Although i believe it is classic mechanic, as i remember using it in PoP to do Grp Aegos, and in order to fix mobs is there anyway to make mobs have a second mana spell check before the spell land after the casting timer?
Also on a side note that is what happens with clickies, that fail to land but still count a charge, which was added later a second check to avoid that to happen to not lose reagents or clickies,
accordingly to nilbog was pending to fix.