Aces High

While attuned, if an ally is actively wielding another Ace weapon/item (Ace of Hearts, Ace of Clubs or Ace of Spades) this shield, the Ace of Dimond's, grants +3 to AC. Ace of Diamonds will also score a critical hit if you role an 18 or above.

Gambler's Fervor

Ace of Dimond's allows its wielder to form a magical barrier of force  in a circle of radius 10 feet around him/herself for 1 round. This costs 1 of this shield's 2 charges. Charges reset at dawn. While surrounded by this  wall of force spells of levels 2 and below are reduced in damage by 75% and physical damage that would total 10HP or less is blocked entirely (strikes that would cause damage of more that 10HP are considered to overwhelm the shield and are not reduced at all).

Shields require the Utilize action to Don or Doff. You gain the Armor Class benefit of a Shield only if you have training with it.

Notes: Cannot be attuned to a creature that is attuned to another "Ace" weapon