Summoned Skull
Summoned Skull, one of the first duel monsters and one of the most recognizable in the franchise. has a long history of retrains and different versions attached to it. At 2500 ATK and 1200 DEF for a single tribute, Summoned Skull remains perhaps one of the best tribute normal monsters, beating out Red-Eyes Black Dragon in attack, while being cheaper to summon than Dark Magician. However both cards long left Summoned Skull in the dust when it came to support and retrains (you can even fuse Red Eyes with Summond Skull, but the resulting lovemonster still has nothing on Blue Eyes), and while Summoned Skull has received love in recent years it still lacks many of the luxuries those two have gotten. Additionally, the Archfiend archetype has been power crept to absolute shit, with its gambling-based effects just not being very good, fun! But not good and with far little benefit in the current state of competitive.