Thorn Binding

Enchants the plants of an entangled area to grow thorns. It can only be cast on an area where entangle has been cast. Any creature that is restrained takes 1d10 of piercing damage at the start of each turn. Any creature that passes through this area takes 1d4 of piercing damage every 5ft.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the piercing damage increases by 1d10 or 1d4 for each slot level above 1st.