Cold Fog is a spell that grants you a buff that lasts 5 seconds. If you take damage while the buff is up, you are granted a new buff that lasts 15 seconds. This buff replaces Cold Fog with White Death, a 400-potency GCD with no cast time. You can cast White Death as many times as you like before the buff runs out. White Death also applies “Deep Freeze”.
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I wonder what kind of skills we're get from Norvrandt. Goblin Punch is used by the Hobgoblins in the area, so that seems like a given.