Ether Primordial (5e Creature)
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Gargantuan monstrosity, any alignment
Saving Throws Wis +12, Cha +8
Emergency Hibernate When the ether primordial is below 0 hit points but above -290, it does not die. Instead, it returns to the ethereal plane, where it falls into a deep slumber. For every year the ether primordial remains in this state, it regains 5 hit points. The ether primordial awakens again when it has regained all its hit points.
Innate Spellcasting The ether primordial can innately cast the following spells, requiring no components. (1/day) etherealness (3/day) blur, mage hand, teleport
Magic Weapons The ether primordial's weapon attacks are magical.
Ethereal Claw Melee Weapon Attack: +10 to hit, reach 15 ft., one target. Hit: 24 (3d12 + 5) slashing damage plus 6 (1d12) force damage.
Concentrated Cyclone Ranged Weapon Attack: +12 to hit, range 120/300 ft., one target. Hit: 12 (1d10 + 7) bludgeoning damage plus 13 (2d12) force damage.
Force Lash Melee Weapon Attack: +12 to hit, reach 15 ft., one target. Hit: 10 (2d6 + 7) slashing damage plus 7 (2d6) force damage. If this attack hits, any creature other than the ether primordial within 15 ft. of the target must make a DC 17 Constitution saving throw or take 3 (1d6) slashing damage and 7 (2d6) force damage.
The ether primordial can take 1 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The ether primordial regains spent legendary actions at the start of its turn.
In most cases, Primordials are meant to be sources of ancient mystique, rather than something to be faced in a head-on battle. Even if the primordial is a threat, it is kept out of sight, and more of an indirect threat than anything or a force of nature. As such, to give those primordials a stat block would fly in the face of all that. However, there is one case where this is not true.
Ether Primordials usually take the form of some kind of beast made of stars and ethereal force. Most are indeed very old, and quite powerful. However, they are in fact, the weakest kind of primordial. As the Ether Primordial lacks many of the reality-warping effects of stronger primordials, they often have to resort to head-on fights, when they engage in combat at all. However, reality warper or not, Ether Primordials are still primordials. They're powerful ancient beings who have had time to learn the ways of humanoids, and prepare themselves should their lives or their hold on the material plane be threatened. And even if they aren't very powerful reality-shapers, they do have some ability to manipulate the ethereal plane's essence.
Guardians of The Ethereal Plane As their name indicates, Ether Primordials come from the Ethereal Plane. There, they keep a watchful eye over the Border Ethereal. If something capable of wiping out planes, or has some other agenda or ability that would cause some kind of cosmic disruption, comes out of a portal somewhere these primordials team up to terminate it before it can get to another plane.
At least, that's what they do in theory.
Accidental Planar Travelers In practice, the more inexperienced Ether Primordials, or even just ones that have not established a lair, could get caught in ether cyclones like anyone else. When they end up on the Border Ethereal of some place, the first thing they do is try to find someplace to rest for a little while, maybe hibernate, before trying to return home. However, like how cults spring up around mummies and krakens, the primordial might find itself an object of worship before it can do so. In such an event, lawful-aligned Ether Primordials feel obliged to stay and guide these cults.
Particularly unlucky Ether Primordials might find themselves hurled into the Astral Plane.