Do Dart Traps(poison ones) work instead of Lihzard Traps? I don't have the Picksaw, and Plantera still isn't defeated.
I'm wearing Nebula armor with Valhalla Knight on as cosmetic. No mods. The backgound walls are natural ones, unless those created with the Clentaminator aren't, and slimes are able to spawn there. Also, there aren't even any walls in front of the spawning space.That's the Valhalla Knight armor you have on right? You aren't using mods right?
I see no reason why you're having trouble. The background walls I assume are naturally placed walls, so they shouldn't interfere with spawns.
The sequencing of the hoik teeth seems to be good. Off when the upper surface is off.