Shapechanger. The Seraphim can use its action to polymorph into a beast form that resembles a cat (speed 40 ft. climb 30 ft.), a owl (5 ft., fly 60 ft.), or a sea snake (10 ft., swim 40 ft.), or back into its true form. Its statistics are the same in each form, except for the speed changes noted. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Magic Resistance. The Seraphim 's has advantage on saving throws against spells and other magical effects.

Familiar. The Seraphim can enter into a serves to another creature as a familiar, forming a telepathic bond with its willing master. While the two are bonded, the master can sense what the Seraphim senses as long as they are within 1 mile of each other. While the Seraphim is within 10 feet of its master, the master shares the Seraphim's Magic Resistance trait. If its master violates the terms of the contract, the Seraphim can end its service as a familiar, ending the telepathic bond.

Bite (Beast Form only). Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 5 (1d4 + 3) piercing damage, and the target must make a DC 11 Constitution saving throw, taking 10 (3d6) radiant damage on a failed save, or half as much damage on a successful one.

Invisibility. The Seraphim magically turns invisible until it attacks or until its concentration ends (as if concentrating on a spell). Any equipment the imp wears or carries is invisible with it.