Thank you for your comment!

Yes, I have tested Heartsteel on Mordekaiser before and it's fun and can work quite often but I do not recommended to build against a team that does damage based on Max Health such as Gwen, [Lillia]], Vayne etc. Still, Jak'Sho, The Protean is still current best Mythic Item for him as it gives you strong resistances and also has a strong passive that also works well together with your Realm of Death.

Once again, thank you for your nice comment! :)

It's true that he only receives his passive from larger monsters in jungle from not long patches ago but still, Mordekaiser is still OP in jungle. The best way in jungle is to clear small minions first before applying your passive and then kill large monster last so that your passive is still active. He is still strong and underratted jungler but if you don't want to play with him in jungle, then you can play him in Top lane only, it's up to you. And please, next time, comment only in English because I don't understand other languages. :)