Shield of the Realm
Artifact — Equipment
If a source would deal damage to equipped creature, prevent 2 of that damage.
Equip 
Benalish glazeplate is stained with salts from the Rift Era and enchanted to deflect blows.
Illustrated by
Dominaria#228UncommonEnglishLegality
Rulings
Apr 27, 2018
If multiple sources would deal damage to the equipped creature at once (for example, several blocking creatures), 2 damage from each of those sources is prevented.
Apr 27, 2018
If a creature is equipped with two Shields of the Realm, 4 damage will be prevented. Three Shields of the Realm will prevent 6 damage, and so on.
Apr 27, 2018
If multiple replacement effects would modify how damage would be dealt, the controller of the permanent being dealt damage chooses the order in which to apply those effects.