Question

This is a little spoiler but I'm not going to have him go through with natsu and the others or live a few hundred years untill cannon going to have him work with zeref and make a clone of himself so what should it have?

The byakugan that will evolve into the tenseigan

Or

The Sharingan. I based it of the Triquetra symbol.

Mangrkyou sharingan apperance: Triquetra Symbol but with the circle on the outside of the triangle. The symbol is black and everything else is red.

Gains Wind, Water and Earth release once awakened.

Left eye abilitys: Called life-death-rebirth.

First Ability, Life: Shows someone's intire life. The user is able to use this to distract someone.

Second Ability, Death: It can show the person who you use it on experience many deaths.

Third Ability, Rebirth: It can completely change and or edit someone's memory's making them rebirth into a completely different person.

Right eye ability: past-present-future:

First Ability, Can see events of the past, present and future but it is random.

Second Ability, Time-Slow: Able to slow down time to a 1/4th of a second on first use. The amount of slowing down time deepens on the user. You can slow down a person to the point it feels like they are frozen in time.

Third Ability, Protection: Puts down a rune of protection on touch. This rune is in the shape of the Algiz. This seal gives the person or thing a shield of protection that can block physical and non-physical attacks the more chakra put into the rune the more it can protect the person or item.

And yes he will awaken the Eternal Mangrkyou sharingan and yes it does get stronger.