Advanced Guard

Shield Wall. If 4 or more guards position themselves 5ft. from each other in a straight line, they can use their action to form a shield wall. While in a shield wall, each guard's AC increases to 19 (bonus does not apply to attacks to the rear, but does to the sides), they must move as one unit, they cannot move more than 10 ft. per turn, they may only make melee weapon attacks with a spear.

The shield wall is broken if: there are less than 4 guards left active in the wall, a guard is killed and the wall cannot be reformed in one turn, or a creature succeeds on Athletics (Strength) check contested by 3 other guards rolling with advantage. 

Spear. Melee or Ranged Weapon Attack: +4 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 5 (1d6 + 2) piercing damage, or 6 (1d8 + 2) piercing damage if used with two hands to make a melee attack.

Longsword. Melee: +4 to hit 5 ft., one target. Hit 7 (1d8 + 2) slashing damage, or 8 (1d10 + 2) slashing damage is used with two hands. 

Longbow. Ranged Weapon Attack: +3 to hit, range 150/600 ft., one target. Hit 5 (1d8 + 1) piercing damage

Shield Wall. If 4 or more guards position themselves 5 ft. from each other in a straight line, they can use their action to form a shield wall.

Protector. While in an active shield wall, the guard can use its reaction to impose disadvantage on attacks against creatures within 5 feet.