The Tavern

Why is it that the Wandering Mushroom minions evolved via Fedhas stop moving when an enemy is in sight?

That's their gimmick; they only stalk you (or follow you, if allied) when you (or in the case of alliance, your enemies) are out of sight.

Personally, I find it awesome. It's pretty easy to control who gets the last hit (preferably the player, for full EXP), in comparison to other minions.