This is a brilliant idea and really well constructed. I do have some suggestions for name replacements however.
-"The River" is a rather bland name and doesn't really refer to any sort of hellish dimension. I'd like to submit "The Styx" as some have mentioned before. Whilst it does grant immortality and may not be consistent with mythology it wouldn't be the first. Wyverns are depicted as snake like beings in Terraria but when speaking lore wise they are closer to serpents.
-"Aether" can refer to a lot of things and is a good name. I think it is clever but I think "Ambrosia" would be equally grand. In mythological terms the actuality is that it grants immortality in a similar manner to the river Styx. However many speculate that because it is the "nectar" of the gods (even if it may be known as a food in some instances) it will kill any mortal upon consumption due to their inferiority to the gods.
(This has been overkill w/Teal)
-"The River" is a rather bland name and doesn't really refer to any sort of hellish dimension. I'd like to submit "The Styx" as some have mentioned before. Whilst it does grant immortality and may not be consistent with mythology it wouldn't be the first. Wyverns are depicted as snake like beings in Terraria but when speaking lore wise they are closer to serpents.
-"Aether" can refer to a lot of things and is a good name. I think it is clever but I think "Ambrosia" would be equally grand. In mythological terms the actuality is that it grants immortality in a similar manner to the river Styx. However many speculate that because it is the "nectar" of the gods (even if it may be known as a food in some instances) it will kill any mortal upon consumption due to their inferiority to the gods.
(This has been overkill w/Teal)