Lava Killing Mechanism
The idea of a Lava killing mechanism is to simply burn the mobs to death. My favourite of all the different ways to kill mobs.
The way to achieve this is to place lava above a sign (or ladder) so it does not flow down, if you force a mob into this then it’ll look like it’s head is in the lava when the rest of it’s body isn’t. This will cause the mob to die without causing the drops to burn up in the lava also.
You can create this device simply by creating a channel at the end of your trap and flowing it into a “dead end”. Then at this “dead end” put a 1×1 flow after your channel runs out of water, at a right angle. (This is for your items to get out). Above the last block in your “dead end” you’ll want to place some signs (or ladders) around on the wall, (two on the back above the out flow, two on opposite sides one block back and one block higher from the last two), this will be to contain the lava. Then place two source blocks of lava in the gap above and behind the signs you just placed. The lava with just appear to float there. If any mobs are pushed into that, they will in effect have their heads burnt off, this includes you! So watch out.
It should look like this: