Shatterskull Smashing isn't working. It will get to the point where you are supposed to assign damage, and then not let you click "Accept." Because of this, I had to concede a Bo3 match-up in Ranked.
[Deleted User] commented
The Accept button will fill in once you assign all of the damage the spell will deal. If X=6 or more it will deal double X so you need to assign 12 or more in those cases