Alien X

Celestial Form. Alien X's physical form is entirely invulnerable to all forms of damage and cannot otherwise lose Hit Points, die, be annihilated, or otherwise erased from existence. Alien X thus ignores effects which destroy universes, multiverses, timelines, dimensions, planes, et cetera. Alien X's body is rigid, and a DC 30 Strength check must be made in order to shove it or otherwise cause it to move. 

Celestial Nature. Alien X requires no food, drink, rest, sleep, or air, and can survive in the vacuum of space.

Multiple Indecisive Personalities. Alien X possesses multiple personalities, in addition to the Omnitrix's user, as a regulating measure on its nigh-omnipotent power. The triad of personalities is Serena, the Voice of Love and Compassion, Bellicus, the Voice of Rage and Aggression, and the Omnitrix's user, the Voice of Reason. Anytime that Alien X takes an action, bonus action, free action, reaction, moves, or otherwise does anything besides exist, the Omnitrix's user must make two Charisma (persuasion) checks (DC determined by the Dungeon Master on a case-by-case basis) to convince both Serena and Bellicus. If either check fails, Alien X does nothing.

Spellcasting. Alien X is a 20-level spellcaster. Its spellcasting ability is Charisma (spell save DC 26, +16 to hit with spell attacks). Alien X can innately cast any spell it knows, requiring no components or spell slots. Alien X knows all spells. Finally, spells cast by Alien X supercede anti-magic fields and similar effects, and occur regardless.

Multiattack. Alien X makes two Godlike Slam attacks.

Godlike Slam. Melee Weapon Attack: +16 to hit, reach 5 ft., 1 target. Hit: 31 (2d20 + 10) force damage. 

Spell. Alien X casts a spell it knows. If the spell normally has a casting time of longer than one action, it only takes one action.

Godlike Power. Alien X creates an effect or performs an action listed below:

• Alien X reverses the flow of time and forces a reroll of any roll made within the last round (including its last turn). Reality reshapes itself to accomodate the new result. For example, Alien X could undo an opponent's successful save, a foe's critical hit, or a friend's failed save. Alien X can force the reroll to be made with advantage or disadvantage, and Alien X chooses whether to use the reroll or original roll.
• If Alien X is in a universe that has been destroyed (i.e., the void that remains after the universe's destruction), it recreates the original universe. There are small differences between the original universe and the recreated one, as determined by the DM, but the recreation is effectively accurate to the original. Time continues from the point right before the original universe's destruction.
• Alien X chooses a creature that it can see within 120 feet of itself. If the creature has 100 hit points or fewer, it is instantly annihilated, dying and leaving no body behind. 
• Alien X creates three duplicates of itself, each appearing within 60 feet. The duplicates all have the same stats as Alien X, and are controlled by Alien X, acting on Alien X's turn in initiative. Alien X can have only three duplicates at a time, and they disappear after 1 minute (or when Alien X forcefully dismisses them as a free action). The three duplicates are similar to Alien X in all but a few ways:
  • The duplicates cannot cast spells or use Alien X's Godlike Power ability. They also do not have their own turns in initiative or their own reactions (thus they could not use Alien X's Interpose reaction). 
  • The duplicates do not have their own respective personalities; they act more so as physical extensions of Alien X's own body, not separate entities in and of themselves.
  • In order to cause all three duplicates to act, the Omnitrix's user must make two Charisma (persuasion) checks as a bonus action to have Serena and Bellicus agree. All three duplicates can take the same general course of action or separate ones, as determined by Alien X. 
• Alien X performs another action beyond the scope of its other written abilities. State what you want to occur to the DM as precisely as possible. Unlike the Wish spell, as long as you succeed on both Charisma (persuasion) checks, Serena and Bellicus both interpret your stated course of action as you prefer, accouting for things you could not possibly think of. For example, if you wished for a simple glass to be filled with water, both Serena and Bellicus would account for the density of the water, the acidity of the water, the temperature of the water, et cetera, and would do so to your preference. 

Teleport. Alien X teleports to an unoccupied space it can see within 120 feet of itself.

Interpose. When Alien X sees a creature be hit by an attack within 120 feet of itself, it can teleport within 5 feet of that creature and interpose itself between the attack and the target. When Alien X does this, the original target takes no damage and Alien X becomes the new target of the attack.