Bind Together

Choose two creatures within one size of each other, that you can see within range. A magical tether that can phase through solid objects forms around each of them and binds together. Each creature must succeed on a dexterity saving throw or be bound by the tether to the other creature. If either creature succeeds on its saving throw, the spell fails. On success, the creatures will be instantly pulled toward each other at rapid speed until they collide, unless they are already within ten feet of each other. On collision, the creatures each take 1d6 bludgeoning damage for every five feet they were pulled, and will not be able to move more than ten feet apart for the duration of the spell, any attempt to move or teleport within the same plane will result in them being rapidly pulled back together. Teleporting to another plane will cause the spell to end instantly. If the two creatures are prevented from being brought together by a large obstruction in the path of the tether, each one will be pulled up against the obstructing object towards the other creature, as if being effected by very strong gravity. a creature in this state will be treated as paralyzed. The spell has no effect on gargantuan creatures.

At higher levels: for each level this spell is upcast above 4, an additional creature may be bound. When the spell is cast in this way, only two creatures need fail the save for it to work. Every creature is pulled toward the center of mass of all creatures effected. All creatures must be within one size range. [large and medium, or medium and small, for example.]