Spongify, Cushioning Charm, Arresto Momentum? Clever move, dear Hogwartian. You know your Whomping Willow, but the charms aren’t enough for it to fully slow down. The tree has no means to defend itself from the spells thrown at it, however, you can be sure that it can do more damage than you imagine if provoked further. The spells did its thing, but again, it wasn’t enough to stop the Whomping Willow from being violent. A quarter of it were in slow motion, but the rest was in full swing.

THWACK!

And there goes a good amount of smashed phials on the ground. The tree did not like being attacked...or tickled, or have a part of it slowed down and cushiony. Slow-moving or not, you must start summoning your ingredients and start brewing before all of it become useless for potion-making.

Unless you have another clever idea in mind to get past the Willow?