Valkyrie

Divine Awareness. The valkyrie knows if it hears a lie. Additionally, it knows if a creature is cowardly and if it fights honourably.

Angelic Weapons. The valkyrie's weapon attacks are magical. When the valkyrie hits with any weapon, the weapon deals an extra 4d8 radiant

Chooser of the slain. When combat begins the valkyrie chooses 1d4 humanoids it can see. Until combat ends When those creature take any damage they take the highest number possible from the damage dice and they automatically fail death saving throws. If a creature dies while under this effect the number of einherjar (I also created a stat block for the einherjar) that appear when the valkyrie uses its call einherjar increases by one

Innate Spellcasting. The valkyries innate spellcasting ability is Wisdom (spell save DC 18, +9 to hit with spell attacks). The valkyrie can innately cast the following spells, requiring no material components:

At will: detect evil and good, bane, bless, heroes feast 

1/day: raise dead, blade barrier, flame strike, commune  

Magic Resistance. The valkyrie has advantage on saving throws against spells and other magical effects.

Multiattack. The valkyrie makes two greatsword attacks.

Greatsword. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 30 (6d6 + 9) slashing damage + 16 (4d8) radiant damage 

call einherjar (1/day). The valkyrie summons a number of einherjar equal to 2d4 + a number equal to the number of creatures that have died while under the effects of chooser of the slain. They appear in unoccupied spaces within 70 feet of the valkyrie, whom they obey. They take their turns immediately after the valkyrie. Each lasts for one hour, until it or the valkyrie dies, or until dismissed as a bonus action.

chosen for death (Costs 1 Action). The valkyrie chooses one creature it can see. The creature then provokes opportunity attack for all creatures with 10 feet of it. 

Summon einherjar (costs 1 action). The valkyrie summons a single einherjar in an unoccupied space within 5 feet of it. The einherjar obeys the valkyrie and takes its turn immediately after being summoned. It lasts for an hour, until it dies or until the valkyrie dismisses it.

berserker aura (costs 2 actions). For the rest of the round the valkyrie and any ally’s within 30 feet of it have a 2d8 bonus to all damage they deal and they have resistance to bludgeoning, piercing and slashing damage.