It sounds like you're referring to a Minecraft Halloween ritual involving a Lovely Craft (possibly a modded or themed server) and a piston trap that is "cracked" (either damaged or cracked in texture, or a trap that triggers when cracked).
Set the trap trigger
Connect the piston to a pressure plate or tripwire that looks "cracked" (use cracked stone bricks as flooring around it). It sounds like you're referring to a Minecraft
Engage in the piston scene; once the character reaches the climax, the ritual completes and the Jack-o'-Lantern Girl is permanently unlocked. Achievement Requirements once the character reaches the climax
Materials:
— Written for lovers of Minecraft, Halloween, and clever redstone. and clever redstone.