Mc won't know what universe he reincarnates at at first, he just starts in an isolated swamp(yes, shrek's swamp. Shrek was never born in this universe) and trains his a*s off. Mc starts off with his maxed out vanilla(mostly) skyrim character (i am still in doubt of the race, probably either argonian or khajit, maybe orc), but with him not knowing if he landed on marvel, dc, warhammer 40k or worse, he spends a large number of days getting even stronger then he was at the game. Mc builds a house for himself(heartfire dlc style) with farms for crops and animals(animals got found in the swamp). Mc's character is completly imune to magical attacks(a bug involving the "atronauch" perk beeing taken while under the effect of a "fortify destruction" potion boosted by the restoration potion loop glitch. Side effect is that you become unable to cunjure stuff(atronauchs, undead, daedra, bound weapons, durneviir, etc(game counts "having a summoned ally active" as a debuff, so magic absorption nullifyes it))) and a werewolf vampire lord hybrid(bugs for this are unreliable, so lets go with the "mod" excuse here) that can regen mana in daylight(this is a bug I myself found by acident but was unable to replicate. Pretty much the -100 percent mana regen of sunlight gets calculated wrong, i do not know if normaly it is calculated multiplicatively or just in the end of the equation, but point is that having a +20 percent mana regen item on your character won't let them regen mana in sunlight normaly, yet this character of mine does! While all my other vampire characters get 120 mana regen in the dark and 0 in sunlight, that one gets 120 in the dark and 20 in sunlight. I have no idea what i did but it realy happens with this one character of mine, and with restoration magic i then have a way to regen hp in the day, add the perk that makes healing regen stamina too and i have a way to replanish all 3 during daytime). Mc won't have any items from skyrim and no way to get them, as the daedra merchant is something mc won't have acess to(mc both won't have summons due to the side effect of his magical immunity, and because acording to lore, mc REALY does not want the inhabitants of oblivion to know about the existence of other worlds, especially one where mc is at), and therefore he has 0 soul gems of any kind and no way to use enchanting, but, during mc's training, he was able to make a bootleg version of it using just mana and no souls, this version is far weaker then enchanting in the game, it also does not allow all the effects mc normaly has acess to, and lastly, all "pseudo-enchantments" are temporary
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Mc discovers he is in shrek world when a scared donkey(yes, THAT donkey) that is beeing chased by medieval knights rans towards him one day and hides behind his back, and the group of knights then try to arrest mc and the donkey on orders of "lord farquaad". Mc will be the one saving fiona as he knows that if no one saves her soon, then her parents will be signing a deal with rumplestilsken and the world will go to s*it because of it(dangerous for mc? No. And he is well aware that he is way too strong for that verse, but he calculated that it would be less annoying to save fiona and risk getting caught in canon, then living in rumple's world)