Permafrost is a Curse.
How to Get Edit
Permafrost should be used as a form of cheap removal. While it doesn't remove the unit entirely it will make it so any unit without Endurance (i)Endurance:
Ready's on each player's turn, and can't be stunned or exhausted by spells or effects. can't attack or block, and it can deal with annoying creatures like Dawnwalker to keep them from recurring.
Created By Edit
When Permafrost is removed, the unit can attack and block immediately.