Mekk-Knight Blue Sky (SDBT-EN018) [Structure Deck: Beware of Traptrix]

If 2 or more cards are in the same column, you can Special Summon this card (from your hand) in that column. You can only Special Summon "Mekk-Knight Blue Sky" once per turn this way. If this card is Normal or Special Summoned from the hand: You can add "Mekk-Knight" monsters with different names, except "Mekk-Knight Blue Sky", from your Deck to your hand, equal to the number of your opponent's cards in this card's column. You can only use this effect of "Mekk-Knight Blue Sky" once per turn.