In Frost’s Arctic Anarchy variation, she gains access to Icequake. This is a divebomb Special Move that allows her to attack from the air.
Icequake can be difficult to punish, or even safe, depending on the height and distance that it’s used. When spaced out, it can be up to -8 on block. If you block the Icequake standing, it will create pushback which means you won’t be able to punish with a jab. To make punishing easier, block the Icequake low. This will cause less pushback on block.
When used at a distance, the Icequake becomes a low-hitting slide attack. This makes Frost safe at -7 on block.
There are a couple of ways to punish this. Jumping back will avoid the Icequake and allow you to whiff punish Frost upon landing. Even though Frost appears to be on the ground, she will still be airborne. Make sure to wait a bit after landing so that you get a grounded punish which will deal more damage.
Similarly, Short Hop will also avoid the Icequake. This will allow you to land faster for a punish.
The last way to punish Icequake is to Flawless Block it. If Flawless Blocked, Icequake becomes -17 instead of -7.