harry vs snakes

I closed my eyes for a second that felt a year long, and gathered together
enough will to attempt to disrupt the Denarian's spell. I formed the
counterspell in my head, and hoped to God that I didn't misjudge how much
power I'd need to undo it. Too little and the spell might actually get
stronger, like steel forged in a flame. Too much, and the counterspell could
unleash the power of both spells in a random, destructive flash of energies. I
focused my will on the cloak of serpents over Susan and lashed out at them
with my power, letting loose the counterspell with a snarled, "Entropus!"
The counterspell worked. The serpents writhed and thrashed around for a
second, and then imploded, vanishing, leaving behind nothing but a coating
of clear, glistening slime in their place.