Tomb of Stone

Choose a Large or smaller creature within range. The target must make a strength saving throw or begin sinking into the ground. The target's speed becomes 0 for the duration of the spell, and they sink more after each failed saving throw. After 3 failed saving throws, they have disadvantage on all attack rolls. After 4 failed saves, the target is buried up to their neck, and cant cast spells requiring somatic components. After 6 failed saves, they become completely submerged, leaving only rough rock where the target used to be, and the target begins to suffocate. If the spell continues for the full minute, then the rock is no longer magical.

On a successful save, the loosened earth turns to fine sand until the target escapes, and the target can spend half their movement to step out of the area, after which it hardens into rough stone