More a mobile machine than armor, every set of this armor is the culmination of masterwork after masterwork from almost every field of magical and mundane engineering.
War Machine. The Armor of Power is a Medium size suit of armor that covers the user from head to foot from the outside world, built as so to prevent anyone with horns or wings from entering due to a lack of space. The armor is entered from behind, a hatch opening the armor to entry if the wheel on it is turned. The armor closes upon detecting a person comfortably within it. You cannot wear armor while within the suit, at most a set of civilian clothing. The armor's outermost layer is an inch and a half of adamantium, sheathing the complex machinery that enables the machine to move in the first place. The joints of the armor are necessarily less armored to allow movement, but are minimally exposed. Within the suit, a ventilation system keeps the user somewhat safe from overheating in the otherwise closed thermodynamic system that is the armor's interior. An engine, transmuted to produce endless energy by taking it from a demiplane, powers the suit's actuators, making it capable of running beyond the theoretical heat death of the universe.
Walking Tank. If you are not strong enough to move the armor proficiently, your speed will be 0 upon entering it, and you cannot take actions. If you can wear it, however, the armor grants you an immediate 22 AC and resistance to Bludgeoning and Piercing damage from nonmagical weapons, as well as resistance to Fire damage and all Slashing damage. You may consider your strength as if you have a Strength ability score of 24 while wearing the suit as it is operational. While wearing the armor, you are considered one size larger for the purpose of grappling enemies and for carrying objects. As the armor is adamantine, you are impervious to critical hits, unless a creature beats a DC 23 Perception check if in combat or a DC 19 Investigation check if outside of combat while checking the suit specifically to notice that the joints are not nearly as protected as the rest of the armor. Once this weakness is noted, any creature that knows this may bypass the armor's critical hit immunity by saying that they are aiming for the joints.
Weapon of Mass Destruction. The adamantine fists of the armor are natural weapons, which deal 1d4 + your Strength modifier and automatically hit objects critically. If you grapple an enemy, you may use a bonus action to vent the built up heat of the suit through your suit's arms, dealing 2d8 Fire damage against any one enemy you have grappled with no saving throw.
Antimagic Vulnerability. The suit runs on a magical engine, making antimagic a vulnerability. If the Armor of Power is within an antimagic spell, the suit immediately loses power, and you must spend your reaction activating the manual release within the suit that will eject you prone from the armor in 3 rounds worth of time. The suit shuts down on the round after that, reducing your speed to 0 and preventing you from taking actions that involve physical movement of your limbs. The air filtration system within the suit shuts down due to a lack of power, and the rate of oxygen leaving and entering the suit gives the creature 5 + 2 * your Constitution modifier minutes before they suffocate from oxygen deprivation. You may force the armor into manually releasing if you beat a DC 26 Strength check to force the armor into position to pull the release. This check may be attempted once every minute, as the act is physically exhausting, and a failure reduces your time before suffocation by 2 minutes. Another creature can remove you from the suit by pulling the manual release in your helpless state as an item interaction.
Plate consists of shaped, interlocking metal plates to cover the entire body. A suit of plate includes gauntlets, heavy leather boots, a visored helmet, and thick layers of padding underneath the armor. Buckles and straps distribute the weight over the body.
Notes: Natural Weapon: Bludgeoning, Immunity: Critical Hits, Immunity: Poison, Damage, Buff, Combat, Str. 15 Required, Stealth Disadvantage