ok I put part one on the title because I have two cross over ideas I just had to put the first crossover I would love to see would be a green latern and Dr strange vs sinestro and dormammu.
it sounds like an odd cross over but hear me out. green latern (John or Jordan dose not matter which one to me) are facing sensetro and for some reason they are pulled to another universe, which would be the marvle univers. they are separated and both are trying to comprehend what's going on.
to one's suprises sensetro somehow met dormammu and both were intersed in eachothers powers.both teamed up to take out Dr strange as part of there agreement but luckily green lantern finds Dr strange and now you got a green ring powered by the eye of agamotto vs the Yellow ring with the power of the creator/destroyer. sorry for the long story I was really contenplating on this during work