Sticker Slab | ELEAGUE (Foil) | Boston 2018 can be found in the following: Boston 2018 Legends (Holo-Foil), Boston 2018 Minor Challengers (Holo-Foil), Boston 2018 Minor Challengers with Flash Gaming (Holo-Foil), Boston 2018 Attending Legends (Holo-Foil), Boston 2018 Returning Challengers (Holo-Foil). You can open these cases in-game for a chance to receive this skin.
