Marvel Heroes! The towering baddies are spawning randomly throughout Gazillion's action RPG, and they'll be doing so through next week's patch. After you take a few down, you can bring looted Sentinel Parts to Hank Pym and you'll eventually be able to craft a couple of new items, according to Gazillion's announcement blurb.
The devs have also buffed up X-Mansion loot and released Psylocke as a playable hero available in the game's cash shop. If you don't want to pony up for Psylocke or grind shards to unlock her, you can watch Massively's MJ stream her live on May 24th at 12:00 p.m. EDT.