to tell you about those few cards that are still Archfiend cards (yay, Falling Down abuse! Quite a fun deck if I do say so myself.)
Archfiend” cards are:

*Anything with “Archfiend” in the name.
*A Deal with Dark Ruler
*Axe of Despair
*B. Skull Dragon
*Beast of Talwar
*Fiend Skull Dragon
*Lesser Fiend
*Shadow Tamer
*Summoned Skull
*Toon Summoned Skull

– Kevin Tewart
Now, that list of Archfiends without the “Archfiend” name in the TCG will never increase further. Any more Archfiends that are created will include that in their name. As an added bonus, new copies of ‘Axe of Despair’ also state in their text that they’re always treated as an Archfiend card!