Ah! Good thinking. Water Weapon is very useful here. Waste all the time you like- a Blocker is useless if you are not attacking him, so you have leisure to use such powers, and the more accurate your attacks, the better.
He'll do the Learned Tutor's Block again. However, you roll +3, Cloud! An 18 hits Sinister, and that attack did seven damage to him, as you cut firmly into the arm he was trying to block with!
Ok, he's going to try a Sacred Willow Push back at you.