User blog comment:Mathmagician/Why Dart Traps?/@comment-77.46.204.123-20120106195447/@comment-4674838-20120106211319

As a single player trap, it's a complete waste of time. Want to try maintaining that thing during a blood moon? If you're using it for PvP, it's not an instant kill except against new characters, not to mention the trap itself would stand out like a sore thumb. Any PvP trap that isn't explosives is a stupid trap, if you ask me.

Oh yeah, lava wall traps with pumps will melt items too, so you don't get loot. Not to mention that there's liquid rendering bugs you'll have to worry about, and someone in multiplayer could easily ruin the trap by placing a few dirt blocks. Have fun cleaning up.

Lava is only useful when being used as a thin layer in pits and being used against monsters, not players. Unless your intention is just to kill noobs or something.