Brooch of Shielding

Wondrous Item, Uncommon (Requires Attunement)

While wearing this brooch, you have

If you have Resistance to a damage type, damage of that type is halved against you (round down). Resistance is applied only once to an instance of damage. See also Damage and Healing.

to Force damage, and you have

If you have Immunity to a damage type or a condition, it doesn't affect you in any way.

to damage from the Magic Missile spell.

Source: Dungeon Master's Guide, p. 241