Call of the Deep

The caster channels the power of the deep from it's arcane focus and draws a sigil in the air out of sea mammal grease, and any creature on a 10 by 10 feet area is crushed by a pressure equaled to 100 meters of in water depth. The caster may cast the spell on the same target adding another 100 meters to the pressure, provided it's concentration isn't broken. Creatures inside the zone get their movement speed limited to 5 feet, have disadvantage on attack rolls and take 2d8 force damage for every 100 meters. Creatures become blinded and deafened at 200 meters as their blood vessels burst from the pressure.