WB games is pretty big, with multiple studioes.
Netherrealm. Mortal kombat, Injustice, Batman:arkham orgins.
Monolith. Fear2, Gotham City Imposters, lots of other stuff in the past and recent.
Rocksteady. Batman:Arkham Asylum, City. and upcoming Knight.
TT games. Lego EVERYTHING.
Turbine. D&D online, Lord of the rings Online. Infinate Crisis.
WB games Montreal. Arkham city: wiiu port., Arkham origins. console ports I think.
THIS is Arrowhead.
Makers of Magicka. That should probably tell us more about its design, then Diablo thoughts mentioned. Its a bit odd they didn't include a "From the makers of:"