As a celebration of the game mode's launch, a special multiplayer event is being held for double experience points. (techtimes.com)
Players that attempt to make a run on One Shot mode will be able to earn double experience points until Dec. 29, Monday, at 9 a.m. PST. (techtimes.com)
Special trading cards allow you to buff your attacks or add passive bonuses like double experience points, but that's about it in terms of the depth of the battle system. (metro.co.uk)