Frost Blast does the job rank 1 Frostbolt used to

For years, Frost Mages kept rank 1 Frostbolt on their bars: a cheap, quick slow. Forever penalizes spells cast at ranks far below your level, so Blizzard has added a spell built for that job.

Frost Blast

The 16 October development notes introduce Frost Blast, learned at level 24. It has a 1.5-second cast, deals damage and slows the target’s movement by 40%. It is affected by every talent that affects Frostbolt.

Blizzard’s stated purpose is to provide what rank 1 Frostbolt used to, despite the penalty for down-ranking. It costs more mana than that old rank 1, and it deals a little more damage.

Why the old trick fades

The 1 October notes spelled out the penalty. Spells cast at ranks far below your level get much less benefit from spell damage and have a reduced chance to trigger class abilities and talents. Blizzard’s example was a rank 1 Frostbolt at level 60, which has no chance at all of triggering Frostbite.

The penalty is about damage and procs; the notes do not say the slow itself gets weaker. What a level-60 Mage gives up with rank 1 is its spell-damage scaling and its talent procs, Frostbite included. Frost Blast is meant to remove that compromise, since every Frostbolt talent applies to it.

What it is not

Frost Blast is a utility spell. The notes describe its damage as low, so it is not a replacement for full-rank Frostbolt as your damage spell. They also do not give the slow’s duration, the one figure you need before planning to kite with it.