Holding the Totem of Shielding in your offhand (shield) slot will direct all incoming damage to the totem until it is destroyed.
The default configuration gives the totem 100 hitpoints and absorbs 25% of any incoming damage. This totem will protect the player from a death blow, but unlike the Totem of Undying will not provide healing and regeneration effects upon its destruction.
Totems of Shielding occur naturally in Desert Temples, Jungle Temples and Woodland Mansions. If the Illusioners feature is enabled, there is a 50% chance that the illusioner will drop a Totem of Shielding when killed by the player.