Cloth Armor

Arsenal(You may cast this card from your sideboard.)
Whenever a source would deal damage to armed
creature, prevent 1 of that damage.
Arm {c}({c}: Attach to target legendary creature you
control as a sorcery. As long as this ability is on the
stack, your opponents can't cast spells or activate
abilities.Whenever a legendary creature you control
enters the battlefield, you may arm that creature
as an instant without paying this card arm cost.)