Thorny Vines

As a bonus action, the player can stab the ground and cause thorny vines to erupt in a 15 ft. radius around them - incurring 1d4 piercing damage to themselves as they tightly grip the staff, stabbing their hands. All creatures within the radius must make a Dexterity saving throw. On failure, a creature will take 1d8 piercing damage or will take half as much damage on success. Additionally, on a failed Dexterity saving throw, the creature will be ensnared in the thorny vines - on their turns they must make a Strength saving throw to break free and end the status effect, on failure they take 1d4 piercing damage as the vines's thorns dig in against their struggling.

The thorn's damage increases by 1d8 (1d4 for failing to break free of the status effect) when you reach 5th level (2d8 / 2d4), 11th level (3d8 / 3d4), and 17th level (4d8 / 4d4).