Beatriemoth The Horseman of War

Uncanny armor. Beatriemoth is unaffected by any non-magical attacks.

Demonically bestowed. All  attacks made by Beatriemoth are considered magical for all purposes.

Uncanny strength. When Beatriemoth rolls for a strength check, she always rolls with advantage (Even if she is under the effects disadvantage from other creatures or effects, Including fatigue, spells, and environment).

Demonic berserker. Beatriemoth enters a berserk like state, for 3 turns, lowering her armor AC by 2, while giving her an extra  die of damage to all of her attacks. During the duration she takes half from all incoming attacks excluding psychic damage. If her HP would be knocked out to 0 during this time she is instead put to 1 and gains 1 point of exhaustion as well as is stunned for 1 turn. This ability can only be used 2 times per long rest.

Unstoppable aggression. On the 1st crit of every turn, Beatriemoth will throw out an extra attack right after damage is done.

Beatriemoth Can make two attacks of one weapon per turn.

Berserker sword. Melee Weapon Attack: +6 to hit, reach 5 ft., 1 target. Hit: 10 (1d10 + 5)  slashing damage.  On a roll of 18 or above, the target must roll a constitution saving throw of D/C save 15 or take bleed 4 damage for 1 d 4  turns.

Demonic whip. Ranged Weapon Attack: +5 to hit, range 10 ft., up to 3 targets. Hit: 7 (1d8 + ) slashing damage. This attack can it's an addition to other targets that are within a 5 ft Square around the initial Target. If only 1 target is hit, you can have them roll a dexterity saving throw or  on a failed throw have them be pulled  in front of Beatriemoth. 

Berserker barrage [Fist]. Melee Weapon Attack: +7 to hit, reach 5 ft., 1 target. Hit: 6  (1d6 + 3) bludgeoning damage. If a critical role is made for her attack the target is stunned for 1 turn and the damage is also increased by 2.

Aggressive Opening. Beatriemoth gains opportunity of attack, even if a creature enters her range of  melee attack 5ft.