Source: Mordenkainen’s Tome of Foes p. 199, Mythic Odysseys of Theros
A quote from Mordenkainen
To rise like a phoenix from the ashes—so many use that quaint colloquialism. Little do they know about the true horror of such a rebirth.
Phoenix
Releasing a phoenix from the Inner Planes creates an explosion of fire that spreads across the sky. An enormous fiery bird forms in the center of the flames and smoke—an elder elemental possessed by a need to burn everything to ash. The phoenix rarely stays in one place for long as it strives to transform the world into an inferno.
Elder Elementals
On their native planes, elementals sweep across the weird and tempestuous landscape. Some possess greater power, gained by feeding on their lesser kin and adding the essence of creatures they have devoured to their own until they become something extraordinary. When summoned, these elder elementals manifest as beings of apocalyptic capability, entities whose mere existence promises destruction.
Deadly When Summoned
The methods for summoning elder elementals remain hidden in forbidden tomes or inscribed on the walls of lost temples raised to honor the Elder Elemental Eye. Only casters of superlative skill have even the faintest chance of calling forth one of these monsters, and the spellcaster is often destroyed by the effort. Thus, only the most unhinged and nihilistic members of Elemental Evil cults attempt such a summoning, in the hope of hastening the world toward some cataclysmic end.
Elemental Nature
An elder elemental doesn’t require air, food, drink, or sleep.
