Currently, the Frost Wand only freezes mobs' positions, allowing them to continue attacking such as ranged mobs still being able to shoot or melee mobs attacking when you get close. Consider preventing frozen mobs from attacking, except for Creepers which should retain their explosive ability even when frozen.

This was actually done intentionally as it's meant to be "root" not a full "stun" that would completely disable the victim, as that seemed a bit overpowered (especially when a player is the victim).