This looks like a good time to use lots of luck. And everything else, while he's at it. Even normally useless things like warmth; if his hand is unexpectedly hot it might help distract her, and it's not like it costs him anything.
He waits until Blossom is nearby, then burns atium and charges out from under the chair.

He aims to ram an open vial down where her throat is going to be. She can choke on the glass for all he cares, but he's making sure some of its contents are getting down.