The Ethereal Core is a craftable permanent power-up item that can only be consumed once, and upon consumption, increases the player's maximum mana by 50. There are 2 other items that function identically to this: the Comet Shard and the Phantom Heart. It can only be used once, and after that the player must use one of the remaining items to increase their maximum mana. With all of these, the player's maximum mana is capped at 350.
- If the player attempts to use a second Etheral Core, the custom status message displayed is "You have already used an Ethereal Core. It's best to not use more than you are able to."
- The four items that increase the player's maximum life, as an extension to Life Fruits: the Blood Orange, the Miracle Fruit, the Elderberry, and the Dragonfruit.
- 2.0.2.001: Now uses 20 Fallen Stars in its recipe instead of 50, and no longer uses 25 Meteorite Bars.
- 2.0.1.001: Now mentions in the tooltip whether or not the player has consumed it before.
- Fixed a bug with max mana boost.
- 1.4.1.001: Swapped its mana star texture with Phantom Heart's.
- Now uses 20 Nebula Fragments and 50 Fallen Stars in its recipe instead of 50 and 100.
- Reduced max mana boost from 100 to 50.
- 1.2.2.001: Now changes the visuals of the mana bar when used.
- 188.8.131.521: Introduced.