You target an object or a creature you see within range with a magical, growing spacial distortion. 

Upon casting the spell on a creature, and for all subsequent turns you keep the spell active. Roll 4d12, and add the resulting value to a pool. Upon the spell's end, if the spell did not end by means of a Dispel Magic spell or similar effects, the target suffers Force Damage equal to the pool's value.

Upon the creature perishing during the spell, by its damage, or casting the spell on an object, the target implodes, the spell ends and a Portal to the Astral Plane opens in the position of the target. The Portal is the size of a 15ft cube, and will push all matter within a 50ft radius 15ft towards the center, suffering Force Damage equal to half the value of the pool(rounded down) and falling Prone.

Creatures pushed in the space of the Portal must make a Constitution Saving Throw or be transported to a random location on the Astral Plane. The Portal then closes. The gate is one-way, and cannot be reopened. 

This spell automatically fails if casted on a target inside an area affected by the Dimensional Lock spell.