So, Minecraft.

[DeeBye]

There is a sweet spot with the depth of the water -- and double wide. If the water is deep enough, then the spiders will bounce into the blade.

Yeah, I was playing around with the geometry of the blade today. I lowered the blade by one, and allowed it to extend to 2x2. I also added some glass blocks above the blade so mobs can't try to "swim up" the lava and have their drops burned up.



It also reliably burns spiders, but it also burns spider item drops (not all the time). The drops from tall mobs like creepers and skeletons safely pass under the lava.

It's working a lot better now.