Mana Drain Mob for What?

I've been cruising and enjoying the game, and then I meet this mob in act 2 that sucks all my mana away. It's so fast it just chases me around in circles. The method to defeat it is to keep kiting and get 1 attack off every 10 seconds until it finally dies. This mob ability makes no sense because it removes all of the skills and the methodical play by bricking mana characters. The strategy to defeat a mob like this is to have a build that one shots it... we need to balance this blue mana drain circle so that its not a boring encounter that forces the players to run around in circles. If the act bosses are no match for my character, this random ability shouldn't turn a yellow mob into such a uber cat and mouse boss-like encounter. It's not fun, it's not balanced, it needs attention.

You're meant to stand within the ring, the inside doesn't damage or drain mana.

Agree, mobs with this ability as a sorceress forces me to use staff attack in case I dont have ice wall equipped to imobilize it.

I always keep an auto attack bind and with supports for enemies like these. They don't consume mana and can be spammed quickly.

It's not so bad when it's just one. Either stay outside or inside the ring.
Gets fun when you have the duplicate rare enemy atlas point and both rings overlap while the enemies move faster than you can dodge or run away.