Arcane Protection Shield (Supreme)

This magical coin attaches to your armor or body (your choice) and reshapes into an arcane brand featuring a shield. Upon finishing a short rest, the brand grants you 4d8 + 8 temporary hit points as it forms a thin barrier of protection along your body that can potentially absorb the impact of any incoming attacks.  

Additionally, as a bonus action you can cause the brand to surge with an emergency reserve of arcane energy, granting you 20 temporary hit points in addition to any remaining temporary hit points granted by this item. This feature cannot be used again until the next dawn.

Notes: Bonus: Temporary Hit Points, humanoid, Warding