Guardian Owlbear

Bonded Companion. The owlbear obeys your commands. In combat, it acts immediately after your turn (until 11th level). At 11th level, it rolls its own initiative and acts independently.
Keen Smell. The owlbear has advantage on Wisdom (Perception) checks that rely on smell.
Magic Bond. If the owlbear drops to 0 hit points, it disappears and reappears 8 hours later, fully healed.
Scaling.
This fully grown owlbear is magically bonded to its ranger companion and grows stronger as the ranger does.
Armor Class: The owlbear’s AC equals 13 + the ranger’s proficiency bonus.
Hit Points: The owlbear’s hit points equal 6 × the ranger’s level + the ranger’s proficiency bonus.
Saving Throws: The owlbear adds the ranger’s proficiency bonus to all saving throws.
Attacks: The owlbear uses the ranger’s spell attack modifier for its attack rolls.
Beak: 1d10 + the ranger’s proficiency bonus piercing damage.
Claw: 1d8 + the ranger’s proficiency bonus slashing damage.

Multiattack. The owlbear makes two attacks: one with its Beak and one with its Claw.
Beak. Melee Weapon Attack: your spell attack modifier to hit, reach 5 ft., one target. Hit: 1d10 + PB piercing damage.
Claw. Melee Weapon Attack: your spell attack modifier to hit, reach 5 ft., one target. Hit: 1d8 + PB slashing damage.

Hardened Hide. When the owlbear is hit by an attack, it can use its reaction to add +2 to its AC for that attack, potentially causing it to miss.