Imperial guardsmen

Only if u are attacking space marines

Either the God-Emperor has spared you a thought or a dark entity of the Warp has touched your soul. Regardless of the reason, the universe itself protects as bolter shells and other extremis weapons have a tendency to miss you. A creature proficient with an extremis weapon (usually a space marine) has disadvantage on attack rolls using it when targeting you. While you possess this feature, you cannot wield extremis weapons without a class feature granting their use. In addition, once per short rest you can spend your reaction to have advantage on an ability check, attack roll, or saving throw, or choose to make a creature reroll a successful attack roll that targeted you.