I know how he did it arrtows fire threw moving blocks

I CHALLENGE YOU:to make a trap that when somebodt stands on a pressure plate they are traped and a block of tnt falls from a skylight and none is visible from inside a room (exept the pressure plate of coarse)

CHALLANGE: Make a Hidding pistone house With high Secured Doors With codes and stuff like that

Automatic TNT Cannon = Reloads and fires itself

make a a secret piston door leading to a secret tnt trap
EASY

i chellenge you to make a random system for 2 or more dispensers

Automatick tnt cannon in flat wall

How 'Bout This:
A Cannon That Makes TNT Go Down Into The Ground All The Way To Bed Rock.... Without Blowing Its Self Up...

I CHALLENGE YOU: Make a trap room when you go in, there's motion sensors below the floor that are timed to set off TNT if a code entered on switches is not entered within a certain amount of time. If the code is correct it will open a invisible piston door in the wall leading to a room with cake. :D