Who is effected by skilled dark magician?

The only card that is affected by Skilled Dark Magician is Dark Magician due to Skilled Dark Magicians Effect which is: "Each time a Spell Card is activated, place 1 Spell Counter on this card (max. 3). You can Tribute this card with 3 Spell Counters on it toSpecial Summon 1 "Dark Magician" from your hand, Deck, orGraveyard."