"Your party encounters 3 goats being attacked by an injured troll on a stone bridge. The goats seem to have the upper hand for now using pack tactics, but trolls are dangerous and can regenerate so the battle may quickly turn to the troll's favor. What do you do?"
The troll is actually a druid that was attacked by a group of were-goats. He polymorphed into a troll using his last spell slot when he was at one HP. If the party kills the troll and does at least one HP in excess damage then the druid will shape shift back into his now dead druid body. While the party looks on in surprise by the transformation, the were-goats will bray with fiendish laughter and attack the party with a surprise round.