I just got a question... Does this even count as player killing, because I got banned on .net for making this near my spawn, and I am just wondering...
I don't think so, or at least it shouldn't. Might not of looked at the entire thing before banning you. I've never made one, so I wouldn't know.
If you put it at spawn, it could be seen as it. Players who spawn in it and are then trusted could be killed. Mods will ask players to remove things like this, and if they aren't removed, then the player who built it could be banned.
It's not playerkilling unless it was built with the intent to kill players. It isn't your fault if players kill themselves in it.
There's a chance of the player getting killed in lava. You never know. What if your friend or the player you pranked him with that "lava and water spawn" got killed? At least he didn't die but it was like "Attempted player killing". Tbh im in the mod's side.