Frost Mage Shatter question

[Apatheist]

In theory, if all 3 frostbolts are cast at exactly the same time then they should be in the same batch and receive the shatter bonus if the target was frozen when that batch ended.

I think it also depends on latency. If you have 250-300ms there's a chance the difference might cause your characters actions to be batched separately. The faster your connection is, the less room for variation. If all of your actions are received within 15ms of each other it's more likely they'll be batched together.