ThemanishereThis drop is for a bundle that includes 3 different event decks, each with 60 cards and a 15-card sideboard. There is generally one Event Deck released alongside each Magic set, and we've put together the ones from each set in the Theros block (Theros, Born of the Gods, and Journey into Nyx) for this bundle.
I've changed the description to add a note to clarify this.