Tricky Treat

The Tricky Treat item increases movement by 20% for 4 seconds, and by 4% for 30 seconds (stackable). Duration: 24 hours. You will get an Upset Tummy if you eat too many.

Source
Tricky Treat is a common drop from. The horseman is found in the graveyard wing of Scarlet Monastery during the Hallow's End seasonal event.

When you defeat the Horseman, small pumpkin 'meteors' fall from the sky, landing on the party members. Each of these is a small random number of these treats.