I'd like to use fall damage to kill the mobs because there's less chance of losing items than lava traps, and I have a large ocean where I can build the trap with no dark land within 128 blocks.
Here are a few things that I know probably won't work:
- Water - Endermen teleport when they touch water, their downward teleport range is unlimited, and they can teleport into lit up places, so there's no way to prevent them from teleporting into underwater caves short of finding and flooding them all.
- Depending on mobs walking around - Mobs stop wandering after 5 seconds if the player isn't within 32 blocks, and I'd be at least 43 blocks away at the bottom to ensure that Endermen die from the fall.
- Using pistons to push the mobs out of the trap.
- Crushing Endermen first and then using water to flush out the trap.
- Both require a piston for every block of spawning space
- The pushing design is difficult to scale because for every horizontal row away from the center you need 2 vertical rows.
- The crushing design is only spawnable for a short amount of time in its cycle, endermen will not spawn when it's crushing (20 secs) or flushing.