Looking at this question and this question, it seems like I can activate abilities after blockers are declared (and before damage is assigned).
So if I'm attacking with Scourge of Skola Vale, can I untap it (say with Kiora's Follower) then tap it and sacrifice a creature to pump it with +1/+1 counters, thus doing extra damage?
Would this also work if I'd given it vigilance before declaring the attack?