Ether Elemental (5e Creature)
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Large elemental, neutral
Damage Resistances bludgeoning, piercing, and slashing from nonmagical attacks
Ethereal Form. The elemental can move through a space as narrow as 1 inch wide without squeezing. A creature that touches the elemental or hits it with a melee attack while within 5 feet of it takes 7 (2d6) force damage. In addition, the elemental can enter a hostile creature's space and stop there. The first time it enters a creature's space on a turn, that creature takes 7 (2d6) force damage.
Slam. Melee Weapon Attack: +7 to hit, reach 10 feet, one target. Hit: 17 (2d12 + 4) force damage. If the target is a creature it must make a DC 15 Constitution saving throw or be sent to the ethereal plane. Every turn the creature repeats its saving throw until success or until half an hour has past.
Among the four elemental planes is a theoretical fifth, ether. Most scholars heavily debate the existence of such a thing as it would completely change all they knew of the elements. One of the most pressing arguments for the existence of this fifth element is the elusive ether elemental. A fuzzy humanoid shape made of violent prismatic energy, roaming the ethereal planes. Ether elementals are commonly drawn out by attempts to travel through different planes of reality.