Bone Brambles

You cause large bones that ooze with necrotic energy to magically erupt from the ground in a 30-foot square starting from a point within range. For the duration, these bones turn the ground in the area into difficult terrain.

A creature in the area when you cast the spell must succeed on a Dexterity saving throw. A creature takes 7d4 bludgeoning damage on a failed save, or half as much on a successful one.

When you cast this spell and on each of your subsequent turns, you can use a bonus action to force each non-undead creature in the area to make a Constitution saving throw. A creature takes 2d12 necrotic damage on a failed save, or half as much on a successful one. If a creature in the area is an undead, it doesn't make a saving throw. Instead, it gains 2d12 temporary hit points.

When the spell ends, the conjured bones turn to dust.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the bludgeoning damage increases by 2d4 and the necrotic damage increases by 1d12 for each slot level above 3rd.