This card is quite splashable in most Decks, since its Summoning conditions are easy to meet. Also, even without a Fairy-Type monster to Special Summon with its effect, it is still quite solid at 4000 ATK and DEF.
This card could go well with "Lightsworn" Decks (so long as this isn't milled before it can be used), because the self-milling effects of the archtype fill up the Graveyard quickly.
This card could also go well with "Skull Servants" Decks, because skull servant decks use cards like Chain Destruction to quickly pile up monster cards in the Graveyard.
This card puts no attack restrictions on itself or the targets for its effect, giving it potential applications for an OTK.
All of the "Darklords" are Fairy-Type; some of the "Darklords" can only be Summoned from the hand, meaning that the effect of "Sephlyon" can bring them out. Many of them also have high ATK, even without this card's effect.
This card can be used alongside "Athena" to either Special Summon the monster summoned by "Sephylon" with its original ATK and effect, or another desired monster. This way, you'll inflict 1200 damage each turn. Also, since "Sephylon" is summoning the monster Athena Tributes, you'll gain field advantage as well.