@FishW You've denied the use of entities

I did no such thing! (or at least I didn't mean to)
It does in fact use entities.

@Triatomic Does it have to do with entity collisions?

Nope :)
(any entity the player collides with can be killed, making an inescapable trap kinda tricky)

Pistons are required to make it, but will be removed when it's finished.
Hint: My trap was not possible before 1.9

@Triatomic undThat's a lot of work to make an 8x8x8 cubeefined

There's a few 'blocks' that prevent chorus fruit teleportation. For example water or repeaters, just flood the place!

@FishW im assuming you used like pistons with the hay bales thing

Neat, hadn't seen this before. With the changes to pistons in 1.9 it's fairly easy to ender pearl out though.

@FishW somehow get into a bedrock hole and trap them

Also nope :)

@Triatomic Are we allowed to make holes in the overworld that go into the void?

No, see this thread:
link

@Triatomic Keep in mind, it's nearly or completely impossible to kill a smart player with a trap.

True, theres nothing to stop them tping out before taking damage. However combined regen from a gapple and full saturation is still not enough to regen from harming potions. Even taking the damage cooldown into account

@Triatomic Fill the trap with tons of zombies or something

Nope. You could just kill them and mine out

@Triatomic Or did you use some piston based contraption which pushes them so they can't mine

Also nope. When your head is in a block you can still mine it. I guess with a fast enough cobble gen you might keep them stuck in there but that's not what I did

@Triatomic chorus fruit could be used to escape before death

This can be easily prevented by removing all valid tp spaces around the trap

I think I have created the best possible tpa trap. It puts the player in a 2x2 space where they are unable to break or place blocks. Arrows or harming potions can be fired into the space, and lava can be added at head height for extra fun. I believe that other than tping out or getting another player to dismantle the trap, there is no way out, even with ender pearls.

I wonder if anyone can figure out how I did it.

@jamlbon @NutjobBob this is slightly irrelevant but why were tour transfering the elder guardian

I wanted a fishy for my pond

Put him in a boat and he'll be your friend forever...

@Nysic Elder guardians aren't killed by the item clear.

Are you sure? I went to the monument pictured with the intention of getting an Elder Guardian to transport to a lake elsewhere. I didn't kill any of the elder guardians, and they were definitely there where I arrived. The item clear happened, and they were not there any more.
Guardians and elder guardians have the same game ID, the elder part is stored as entity data. Such that /kill @e[type=Guardian] kills both elder and normal guardians.

@Nysic it comes as a nice breather to the server every hour.

Yes, but only for 5-10 minutes out of each hour, after which the numbers are back up again. Is that actuall worth it for the server?

@Synchronous
That's a neat way to do it, it's good to know that it's possible. However, any guardians added to the notElder objective that are unloaded when the kill command runs will not be killed, and will not be removed from the objective, it'll keep adding more guardians that may never be removed, which might be a problem.