Cannot be Special Summoned. If this card is Tribute Summoned: You can Special Summon "Darklord" and/or "Fallen One" monsters from your hand and/or Deck, up to the number of Effect Monsters your opponent controls. While you control another "Darklord" or "Fallen One" monster, your opponent cannot target this card with card effects. Once per turn: You can send cards from the top of your Deck to the Graveyard, equal to the number of "Darklord" and "Fallen One" monsters on the field, and if you do, gain 500 LP for each "Darklord" and "Fallen One" card sent to the Graveyard by this effect.
I had 2 in my deck tribute summoned one, and it wouldn't let me activate the second summon. Opponent had an effect monster and I had another Darklord Lucifer in the deck still. Why couldn't I summon the second one?