Tartarean Chains

From birth on a creature is cursed with this ethereal chains that no one can see or interact with. Tartarean Chains are forged by the gods, to make the Titans incapable to return after being beaten.

The Chains alter the appearance of the cursed creature. (if completle removed the creature transforms in a Titan from the pits of Tartaros, Chaotic Evil and Powerfull enough to challenge even the Gods. Your Character changes, you become a reincanation of the Seven deadly Sins.) *see Creature: Titan of Tartaros*

The chains are sealed twice.
After opening the first seal you enlarge and become stronger in every way. While containing your own charakter and emotions.
After opening the second seal you enlarge even further and become even stronger in every way. While containing most of your own charakter but only the strongest emotion you have at the time. This emotion gets enhanced to an extreme, anger turns to mindless rage without mercy, sadness turns to hatred, happyness to Pride etc. (Alignment or Moral can be forgotten in this state. But you will remember everything you did later.)
After finding a way to remove the chains completely you become a Titan from Tartaros,  meaning your now a 150 feet tall, chaotic evil creature powerful enough to challenge even gods.

Seals reform after 1 hour unless the Chains where removed.
After a seal is broken, others may hear a loud shattering of metal. If you managed to take the chains of, the chains become visable and materialize, but they have the proportions of your new form. In other words dozents of tons of metal hit the ground from hights up to 50 feet.

Weight of the World

From 1 level, your chains keep your physical and spiritual powers down. But after thousend of years and other creatures before you, some of there power is no more. Some of the Power withhin you leaks out making you stronger than you seem. You gain the feat tough.

Pride of the Great ones

At 1 level, the Tartarean in you hates beeing weaker than other, it hurts there pride everytime. So it decides to grant you a glimpse of their power that gets through the chains.
You have advantages on your savingthrows against beeing frightened, restrained, grappled and beeing intimidated.

Immovable Presence

Starting at 6th level, your simple conviction is enough to bend space and time at your will, you can use your reaction to become invulnerable and immovable. You can use this effect once before needing a longrest to recharge it.

Unleash the Power

At 14th level, you have the power and knowledge to open the first seal that hold your ancient power back. You can choose to open it in a 5 minute long ritual.
When it opens you get:

-Enlarged
-every spellslot is automatically 1 level higher
-you can hold Concentration twice at a time, but have disadvantage for the saving throw if you get interrupted and lose focus for both
-your AC rises by 1

This effect ends after 1 Hours and can be used again after finishing a long rest.

Broken Cage

At 18th level, you have the power and knowledge to open both seal that hold your ancient power back. You can choose to open it in a 10 minute long ritual. 
When it opens you get:

-Enlarged twice
-Double your HP
-every spellslot is automatically 1 level higher
-every spell you cast is 1 level higher.
-you can hold Concentration twice at a time and can't get interrupted.
-you gain disadvantage on dexterity Saving throws
-your AC rises by 3

This effect ends after 1 Hours and can be used again after 7 days and nights.

After opening the second seal you enlarge even further and become even stronger in every way. While containing most of your own charakter but only the strongest emotion you have at the time. This emotion gets enhanced to an extreme, anger turns to mindless rage without mercy, sadness turns to hatred, happyness to pride etc. (Alignment or Moral can be forgotten in this state. But you will remember everything you did later.)