Pendant of Invincibility

This adamantium piece of jewelry radiates Transmutation magic when Detect Magic is cast upon it. The pendant has runes written on the back. The front is engraved with an armored giant. Using a bonus action and uttering the command word, your body becomes covered in adamantium with the pendant centered on your chest incorporated into the armor. When you are armored:

• Your movement is halved and you have disadvantage on Dexterity checks and Dexterity saving throws. You do not gain benefits from dodge-like or evasion-like features. Your strength is increased to 24. You have advantage on Strength checks and Strength saving throws.
  
• Your AC is 24
  
• You have resistance to all damage except psychic damage.
  
• You cannot be knocked prone or grappled.
  
• Your body becomes a juggernaut that can deal significant damage. Your attacks overcome resistance and immunity to nonmagical attacks and damage. It also overcomes resistance to any form of damage.
  
• You make two attacks; each attack deals 2d20 force damage. If you succeed with both attacks, the creature must succeed a DC 20 or be grappled. A creature from size huge and below can be grappled by you. Each round a creature is grappled, it sustains 3d10 force damage.
  

You can perform this transformation once weekly. The transformation lasts for 10 minutes. You can end the transformation sooner by using a bonus action. While in this form, you cannot cast spells that require somatic or material components. If you are lowered to 0 hit points while you are transformed, the pendant is transferred to the creature that dealt the final blow and it gains knowledge of how to use the item and can use it immediately.