Berserker. The orc adds it's proficiency to damage, and has resistance to Non-Magical Damage.
Aggressive. As a Bonus Action, the Orc can move up to its speed towards an enemy it can see or hear.
2x Battleaxe Multiattack.
Battleaxe:Melee Attack: +8 to hit.
Hit: 22 (3d8+8) slashing damage.
Javelin. (Recharge on 5-6) +9 to hit, Range 40 ft.
Hit: 47 (6d12 + 8) piercing damage.
Fearful Gaze. As a reaction, the Orc can frighten the last target that dealt it damage it if they fail a DC 16 WIS Save.
Swarm Size and Shape. There are 16 creatures in this swarm, and they occupy 16 tiles or 12 hexes contiguously.
This swarm's stats are based on those of a Zombie, CR 1/4.
Undead Fortitude. If damage reduces the zombie to 0 hit points, it can make a Con saving throw with a DC of 5+the damage taken, unless the damage is radiant or from a critical hit. On a success, the zombie drops to 1 hit point instead.
Mulitattack. The swarm can make two attacks if they are above 184 Hit Points.
The swarm also makes one attack against every creature within the space it occupies.
Swarm Attack. +5 to hit. This roll is made with advantage if the target has no allies within 5ft of it. Range and special properties match the individual attack.
Hit. 26 (5d12) damage.
Slam Melee Weapon Attack: +3 to hit, reach 5ft.
Hit: 4 (1d6+1) Bludg. damage.
To have an individual creature break out from the swarm, subtract up to 23 HP from the swarm's current total as if it were damage. The individual creature can now act on its own initiative with those hit points using the creautre's individual attack stats.