Lightning Resistant Chain Shirt (Magical). The guard has Resistance to Lightning damage when wearing the armor and is immune to Lightning effects that specifically target metal armor, such as the shocking grasp cantrip. 

Alert. When the guard rolls Initiative, it has Advantage. 

Spear. Melee or Ranged Weapon Attack: +5 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 6 (1d6 + 3) piercing damage, or 7 (1d8 + 3) piercing damage if used with two hands to make a melee attack.

Shock Stick. Melee Weapon Attack: +5 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 6 (1d6 + 3) bludgeoning damage. 

Shock (Recharge 5-6). When the guard hits with a Large or smaller creature with its shock stick, it can use a bonus action to deal an extra 1d8 Lightning damage. The target must make a DC 13 Constitution saving throw. On a failed save, it is Dazed and Slowed until the end of its next turn. A creature reduced to 0 hit points by the LIghtning damage is Unconscious but stable. A Shock stick used by creatures other than an elite guard has 3 charges that reset at dawn rather than the Recharge property.