An archetype usually with Archfiend in their name but some other cards count as them.
I think the reasoning behind this is the Japanese names had atchfiend in them but were changed when translated over so the other languages could still use the card applicable to those monsters
But the mage says "archfiend", Summoned Skull is not that type, we can't special summon or I miss something?
As good as this card would be in Duel Links, the meta is so filled up with position-changing cards that it's better to run Machine King. Or, of course, The Fiend Megacyber due to its Special Summon ability.