Some Lovely Craft mobs (specifically Wolves and Bears) can glitch through a single block if they are jumping. To prevent this, pour a into the pit before baiting. Water prevents jumping, ensuring they stay under the piston.
If you are playing on a or single-player world? lovely craft piston trap achievement guide
Once your trap is wired, it is time to lure a target and claim your reward. Some Lovely Craft mobs (specifically Wolves and Bears)