Rastislav
The mc shouldnt worry about lifespan theres a dark elf mage thats thousends of years old whos name ive forgotten so there are magic methods to extend lifespan that on top of his natural lifespan of 2000 years that is going to increase according to the mc thats more than enuf time to figure out how to become ageless or even become god like minomarco
Divayth Fyr is one of the few ancient mers that know the old ways of magic, which includes time-manipulation. That's why he's immortal. He's one of the most intelligent characters from the Elder Scroll lore, and he's also friends with Kagrenac, Yagrum Bagarn (last living dwemer), and he was known for outsmarting gods.
how is he gonna enter the soul cairn you know without dieing also plz let him somehow kill the masters of the soul cairn there is alot of people/souls in the soul cairn that have alot of lost knowledge that could be usefull it might even give + in magnus eyes by remakeing the realm into something like temp place before entering reincarnation like sovenguard