Cranberry Bog

The ground in a 20 foot area, centered on the caster becomes a waist-deep mire, full of strange red berries. Any creature other than the caster that starts its turn in the bog must succeed a STR saving throw or be caught in the swampy dirt, treating it as difficult terrain. The bog spreads along the ground with the caster as its origin, travelling along any surface that a creature can stand on, and bridging gaps and cracks measuring less than a foot across. The marsh does not travel up or through walls or doors, but can travel along the surface of water, as long as it remains in the cylinder.

If wild shaped and concentrating on the spell, the caster may take the following special actions:

 Once at the start of each of their turns, before taking any other actions, the caster may choose a point within the bog to emerge from, regardless of where they are. This does not provoke opportunity attacks.

As a bonus action, the caster can center the bog on their location. Any creatures under the effect of the bog may reroll their STR saving throw. The creature may keep this roll or reroll at the beginning of their turn

When cast at a higher level, the area of the spell increases by 10 feet per level above the first.