Desert Maw

You target a 30 foot cube within range, every creature on the ground within the cube must make a dexterity saving throw or be restrained as the ground beneath them becomes quicksand, a creature can use its action to make a athletics check against your spell DC, if they fail they sink deeper and are still restrained, if they succeed they are no longer restrained, if a creature fails to escape three times it sinks below the surface and begins to suffocate. Any creature within the area ends its turn while the spell is active they must make the save as well as when they enter the area for the first time. The area effected by the spell is difficult terrain. If a creature is underneath the sand when the spell ends they appear on the surface unharmed within the cube at the DM's discretion, if the creature is dead they are instead consumed by the earth and the caster gains temporary hitpoints equal to their level plus the amount of creatures consumed(undead are consumed instantly if they sink but grant no temp hp).