Shared Vitality. This companion manifests as two beasts that move and act independently but share a single pool of Hit Points and one Reaction. Game features and Areas of Effect treat the beasts as a single creature, making one saving throw for both when necessary. Both beasts drop if the shared pool reaches 0.
Pack Tactics. The beast has Advantage on attack rolls against a creature if at least one of the beast’s allies is within 5 feet of the creature and the ally doesn't have the Incapacitated condition.
Primal Bond. Add your Proficiency Bonus to any ability check or saving throw the beast makes.
Actions
Beast’s Strike. Melee Attack Roll (x2):Bonus equals your spell attack modifier, reach 5 ft. Each beast makes one attack (Prime and Echo, respectively), directed at the same target or different ones.
Prime Hit: 1d4 + 3 Bludgeoning, Piercing, or Slashing damage (your choice when you summon the beast). Echo Hit: 1d4 plus your Wisdom modifier Bludgeoning, Piercing, or Slashing damage (your choice when you summon the beast).
Reactions
Coordinated Reaction.Trigger: A creature the companion can see leaves the reach of either beast. Response: The companion takes the Beast’s Strike action.
Beast of the Pack
Medium Beast (Two Creatures), Neutral
AC 13 plus your Wisdom modifier
HP 10 plus five times your Ranger level [Shared Pool] (the beasts share a number of Hit Dice [d8s] equal to your Ranger level)
Speed 40 ft., Climb 40 ft.
Senses Darkvision 60 ft.; Passive Perception 12
Languages Understands the languages you know
CR None (XP 0; PB equals your Proficiency Bonus)
Traits
Shared Vitality. This companion manifests as two beasts that move and act independently but share a single pool of Hit Points and one Reaction. Game features and Areas of Effect treat the beasts as a single creature, making one saving throw for both when necessary. Both beasts drop if the shared pool reaches 0.
Pack Tactics. The beast has Advantage on attack rolls against a creature if at least one of the beast’s allies is within 5 feet of the creature and the ally doesn't have the Incapacitated condition.
Primal Bond. Add your Proficiency Bonus to any ability check or saving throw the beast makes.
Actions
Beast’s Strike. Melee Attack Roll (x2): Bonus equals your spell attack modifier, reach 5 ft. Each beast makes one attack (Prime and Echo, respectively), directed at the same target or different ones.
Prime Hit: 1d4 + 3 Bludgeoning, Piercing, or Slashing damage (your choice when you summon the beast).
Echo Hit: 1d4 plus your Wisdom modifier Bludgeoning, Piercing, or Slashing damage (your choice when you summon the beast).
Reactions
Coordinated Reaction. Trigger: A creature the companion can see leaves the reach of either beast. Response: The companion takes the Beast’s Strike action.
For those who want to add it to your collection: https://www.dndbeyond.com/subclasses/2694280-beast-master-beast-of-the-pack