Army Group

Advance.

Melee Weapon Attack: +2 to hit, reach 100 ft., 1 target. Hit: 20d100 bludgeoning damage.

Ranged Weapon Attack: +2 to hit, range 500/1000 ft., 1 target. Hit: 20d100 piercing damage.

Breakthrough.

The army group can attempt to break through the enemy lines of another group right after a successful advance. 

Melee Weapon Attack: +4 to hit, reach 100 ft., 1 target. Hit: 40d100 bludgeoning damage. 

Ranged Weapon Attack: +4 to hit, range 500/1000 ft., 1 target. Hit: 20d100 piercing damage.

Encircle.

The army group can attempt to encircle the enemy group right after a successful breakthrough. If the enemy successfully retreats, this action cannot be taken.

Melee Weapon Attack: +4 to hit, reach 100 ft., 1 target. Hit: 80d100 bludgeoning damage. 

Ranged Weapon Attack: +4 to hit, range 500/1000 ft., 1 target. Hit: 40d100 piercing damage.

Exterminate.

The army group can attempt to completely destroy the encircled enemies.

Melee Weapon Attack: +8 to hit, reach 100 ft., 1 target. Hit: 160d100 bludgeoning damage. 

Ranged Weapon Attack: +8 to hit, range 500/1000 ft., 1 target. Hit: 80d100 piercing damage.

Retreat.

The group can attempt to make an organized retreat to avoid encirclement. To do that, the group must succeed on a DEX saving throw with a base of 13 right after taking damage from a successful enemy Advance (DC 12), or a successful enemy Breakthrough (DC 17). If the group is encircled, it cannot retreat.