Adam's Aqua Serpent

You summon an elemental serpent from the Plane of Water. The elemental forms a semi-solid floating serpent that circles around a large or smaller creature you can see within range, sharing its space. For the duration the serpent sheds a dim light in a 10 foot radius. When you cast this spell, and as a bonus action on each of your turns until the spells ends, you can choose one of the following actions for the serpent to preform if its within 30 feet of you:

Constrict. The serpent attempts to constrict the creature its circling. That creature must make s Dexterity saving throw. On a failed save, it takes 3d8 magical bludgeoning damage and has disadvantage on attack rolls until the end of your next turn. on a successful save, it takes half as much damage and suffers no other effects. 

Protect. The serpent Protects the creature its circling. Until the end of your next turn, that creature has resistance to fire damage, attack rolls against it are made with disadvantage, and heal for 1d6 + spell casting modifier. 

Reposition. The serpent moves to a different creature that you can see within 60 feet, and starts circling that creature instead. It moves to its new tarfet by the shortest possible route. Each creature of your choice along a 5-foot wide line following the serpent's route must make Dexterity saving throws. A creature takes 3d6 magical bludgeoning damage on a failed save or half as much on a successful one. 

If the creature the serpent is circling dies, you must take the reposition action on your next turn. Otherwise, the spell ends.