Bananaloth

Return to Master. When the bananaloth is killed outside the presence of both its master and its creator (or just one, if the other is dead), it becomes incorporeal until it is back with its master and/or creator again. When incorporeal, the bananaloth has the following traits:

Incorporeal Movement. The bananaloth can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.

Incorporeal Defense. The bananaloth is immune to all damage but force damage (which it has resistance to) and psychic damage. If it is killed in incorporeal form, it reforms after 1d4 hours.

Levitation Beam. The bananaloth shoots a beam of levitation energy at an object, which it can move and manipulate at will. 

Helpful Spellcasting. The bananaloth has the following spells it can cast at will as an action. 

Mage armor (on itself, its master, and its creator), minor illusion, invisibility, mending, healing word. 

Go Serve Master. The bananaloth teleports (as if it had cast the misty step spell) toward its master (or its creator, if they are not one and the same), so long as the they are within 60 feet of each other before teleporting. 

Flee. In response to being dropped to half its hit points or less, the bananaloth moves up to its speed in a direction away from its enemies.

Shield of Service. The bananaloth casts shield on itself, its master, or its creator when they are in hit by a weapon attack or are targeted by the magic missile spell.