Basalt Deltas
"The Nether’s most perilous biome… Ash and smog fills the air with a hazy fog, fire and lava seeping from every crevice. Watch your step, the floor might actually be lava."
Aether Mode makes the lava higher and actually deal damage (it does fire damage, so be warned, Zetterburn has an unfair advantage in Aether mode), and adds Striders that act as moving platforms walking back and forth across the lava.
Also has ambient sounds, though its hard to hear over the music.
Music:
– So Below – Remix (by EksSan)
– Pigstep (by Lena Raine)
– Rubedo – Remix (by EksSan)
(the code for the lava was copied and tweaked from the Greenpath stage by ATalksToSelf)