Not completely new, it's just the mage boss but now it freezes you instead of burning and electrocuting.

Can be found in the Metereological Institute Midpoint 4 (the second institute dungeon, midpoint 4 will tp you just before the boss instead of after it).

The boss is scaled for endgame (the boss is level 350)

Don't worry, it won't debuff your defense on every single attack that hits you, only one attack does it but it doesn't last very long (most attacks will debuff your damage tho).

Will conflict with my Enemies Enhanced mod.