Etched into the amulet you can see what appears to be four beams being blocked by a shield.

The amulet holds up to 10 charges, that are renewed 1d6+4 at the beginning of each day.  A charge allows you to use your reaction to cast Eldritch Shield:  A glowing barrier of magical force appears and intercepts Eldritch Blast beams. Until the start of your next turn, you have a +5 bonus to AC, including against the triggering attack, and you take no damage from an Eldritch Blast beam.

Notes: Buff, Combat, Warding