Primal Guardian

When the guardian becomes Bloodied, it gains Temporary Hit Points equal to half of its maximum Hit Points and is enraged for 10 minutes. While enraged, Hostile creatures within 5 feet have Disadvantage on attack rolls against creatures other than the guardian.

The guardian can't be surprised.

Add your Proficiency Bonus to any ability check, attack roll, or saving throw the beast makes.

Melee Attack Roll: Bonus equals your attack modifier using Strength, reach 5 ft. Hit: 1d4 + 2 plus your Rage Damage bonus Bludgeoning, Piercing, or Slashing damage (your choice when you summon the beast).

Trigger: When a creature the beast can see attacks a target other than itself that is within 5 feet of it. {@actResponse} The guardian takes the damage instead of the target.