Fractine

The fractine has advantage on saving throws against spells and other magical effects.

A spellcaster can use the fractine as a substitute focus when casting the scrying spell or similar magic, provided the spellcaster and the fractine are within 5 feet of each other.

The fractine can occupy another creature's space and vice versa. It can move through other creatures and objects as if they were difficult terrain, but it takes 5 (1d10) force damage if it ends its turn inside an object.

The fractine doesn't require air, drink, or sleep.

Melee Spell Attack Roll: +5 to hit, reach 5 ft., one target. Hit: 24 (8d6) force damage.

In response to being damaged by a creature it can see within 120 feet of itself, the fractine forces that creature to make a DC 16 Constitution saving throw. On a failed save, the creature takes 24 (8d6) force damage. On a successful save, the creature takes half as much damage.

When a Large fractine that has at least 10 hit points remaining takes bludgeoning, piercing, slashing, or thunder damage from any source, it splits into two Medium fractines. The new fractines occupy the space formerly occupied by the original fractine, and each new fractine has hit points equal to half the original's, rounded down. If the original fractine had a creature trapped in its demiplane, that creature is released when the fractine splits, reappearing in an unoccupied space as close to the new fractines as possible.