Batman: Arkham City we caught wind of earlier this month has moved one step closer to becoming official. The Arkham City twitter account tweeted the above teaser image of feet and hammer earlier this morning, immediately proceeded by an unattributed quote: "Don't worry. This is all part of of my plan."
Very mysterious, but given Harley Quinn's historical propensity for comically large mallets, we think inferring her involvement is justified. Personally, we're keeping our fingers crossed for a collection of Whack-A-Mole minigames staring Ms. Quinzel.