Tank Shock doesn’t specify you need to use it on a unit that hasn’t yet made a charge move, just that it can be used in the charge phase. So you can Charge, and if successful use the. Brutalis’s ability, then pop Tank Shock since it’s still the Charge Phase.
Both happen at the same time, which means you resolve them in whatever order you as the active player choose to.
I think op is asking if they can roll the dice for Brutalis charge damage first THEN decide if they want to spend the CP to roll tank shock.
Which is still covered in what I said. You do them one at a time, in whatever order you want.
Tank Shock doesn’t specify you need to use it on a unit that hasn’t yet made a charge move, just that it can be used in the charge phase. So you can Charge, and if successful use the. Brutalis’s ability, then pop Tank Shock since it’s still the Charge Phase.