Also, a Colossal Titan
Phantasy Star Online 2 has gotten some pretty crazy crossovers so far, but this one is probably the coolest. Attack on Titan will be invading PSO 2 in multiple ways, the most obvious of which is new outfit selections.
You'll be able to deck yourself out with Survey Corps outfits, as well as recruit stickers, weapons, Mikasa's hair and scarf, and the Three-Dimensional Maneuver Gear. The best addition though is the appearance of the Colossal Titan, who will "attack" (but not actually attack) the lobby and the background.