Amulet of Bestial Aspect

 Rarity

Creature

Effect 

 Common

 Wolf 

Advantage on Wisdom (Perception) checks when using smell and sound 

Uncommon

Sabre Cat 

Resistance to Cold Damage 

 Rare

Bear 

 Your Constitution score is 19 while you wear this amulet. You also gain the ability to turn into a bear once per day. The Amulet regains this ability at the next dawn

Very Rare

Dragon 

 Resistance to Fire Damage. You gain the ability to use Frightful Presence once per day while attuned to this amulet. Every creature within 60 feet of you must succeed on a DC 17 Wisdom saving throw or be freighted of you for 1 minute. Each creature may retake the saving throw at the end of their turns. The Amulet only regains the ability when steeped in flame for 1 hour.

Legendary

Yeenoghu, god of Gnolls

 While attuned to this amulet you gain the abilities Primal Bloodlust and Insatiable Hunger. When you roll a critical hit you make an additional weapon attack using Primal Bloodlust. When you kill a creature and another creature is within 5 feet of it you may transfer half the damage dealt to the new creature using Insatiable Hunger. 

Curse. While attuned to this amulet you must succeed on a DC 21 wisdom saving throw whenever you take damage in combat. On a failed save, you must attack the creature that damaged you until you drop to 0 hit points or are unable to make a weapon attack against it.