Back with another, interesting entrance. So basically how this works is when you walk through one side, the lave flow is cut off form the top, and the walls push inwards, then retract to get rid of the lava that would otherwise take minutes to disappear. Upon walking through the other side, the lava opens back up. You can make this a Two-Way door by replacing the 1-Bit Memory Cell underneath with your favorite T-Flip Flop. This is great for temple entrances, traps, and adventures alike.