I have 89 mythics, 58 legendaries and 10 epics.
I have a few legendaries that were raised to Mythics: Aborath, Kerberos, Gloom Leaf, Goblin King, Gorgotha, Gar’Nok and Shadow Dragon. I’m missing 1-2 copies of the other.
However, I have no epics that I could raise to Mythics! I’m missing 8-10 for almost all of them…
I think that those will be the hardest to raise, not the legendaries