Centurion

Roman Discipline. The Legionary gains +1d6 of damage on melee attacks when below half health

Lead by Example. All friendly Legionaries within 50 feet gain a +2 bonus towards hitting when making an attack.

Attacking Testudo. When within 5 feet of 3 other friendly Legionaries, they raise their shields above their heads and form a shield wall. All enemy attacks roll with disadvantage to hit Legionaries in a testudo. If one Legionary moves in a Testudo, all others move with it and lose one action on their next turn (as they've already moved) unless it exits the formation.

Use the Whip. All friendly Legionaries within 50 feet must roll a Constitution check higher than 12. If they fail, they suffer 5 points of psychic damage and lose one action on their next turn. If they succeed, they gain one extra action for their next turn, gain +1d4 to any attacks they make on their next turn, and gain an extra 10 feet of movement speed.

Gladius Thrust. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 7 (1d8+3) piercing damage. 

Pila Throw. Ranged Weapon Attack: +4 to hit, range 15/40 ft., one target. Hit: 9 (2d6+3) piercing damage. If the target has a shield equipped, and the hit roll was greater than 8, the shield is now disabled and has a javelin stuck in it. This attack can only be used twice.

Parry. The Centurion adds 3 to its AC against one melee attack that would hit it. To do so, the Centurion must see the attacker and be wielding a melee weapon.