My Sturm has enough +Range on her emblems that she (barely) outranges my heavy (Chieftan), so my Chieftan can (usually) tank for her. And it lets my Sturm function as a back-up tank if Lily goes down. It's good times.

But I got REALLY lucky with my Sturm emblems. The thing about Sturm is that she needs pretty much EVERYTHING on her emblems (she even has terrible range, rotation, and move speed, though it's admittingly a stretch to say she NEEDS those, but they still help), which makes her pretty hard to gear for and practically requires five-star emblems. The fact that she needs all those emblems also means she benefits a ton from getting it all, so if you manage to get that, she's probably one of the best tanks in the game.