So Limbo seems impossible to play to full effectiveness in pugs. Everything I do screws my teammates over but if I don't do it I'm incredibly squishy...
Limbo pops up a lot in Mobile Defense sorties where people just use Cataclysm + Stasis to cheese the whole thing. Your team doesn't have to do much to contribute, but it doesn't really screw them in any way.
I was recently in an interception for the first time since coming back to the game, and there was a Limbo. Apparently at some point since I last played, they gave him a power that freezes all enemies in his bubble and makes it so they can't be damaged. Great job!
It stops 300 (or less, depending on the weapon) projectiles, but you can still melee. Or you can force it to end by shooting a lot to spite the Limbo player, I guess.