Hexproof

{X}, {T}: You get a number of {E} equal to X.

Release It — {T}, Pay any amount of {E}: Add one mana of any color for each {E} paid this way.

Weaponize It — When The Heart of Etheria is put into the graveyard from the battlefield, it deals damage to each player, planeswalker and creature equal to the number of {E} you have.