No, im not gimping the spell, im going by the OP
"He has the SPELLS and POTIONS he had been shown using in the movies."
Firebolt is not a spell. He can summon it, but he cant use it, as he wasnt given it in the OP.
So let me get this straight, he gets lucky and pred falls on his own wrist blades?
Best i can think that works for is letting him be a bit luckier in not being seen. A bit. A. Bit. Not much. Preds thermal will still catch him. I dont see ANYTHING that potion will do.
Copy and pasted from a Harry Potter wiki- " It's meant to be used sparingly, however, as it causes giddiness, recklessness, and dangerous overconfidence if taken in excess."
Harry would be one of those, or he wouldnt be that lucky. Oh, and if he takes enough, its fatal.