Amanda Sefton and Clea are not mutants, plus Clea is sorceress supreme of the Dark dimension. There are not many mutant witches capable of governing Limbo. I can’t imagine Illyana giving Limbo to Selene. Storm doesn’t have the magical skill and the Scarlet Witch did decimation, though she recently redeemed herself with Krakoa. So Madelyne fits the bill perfectly.