I tested quite a lot Defense/Storm on a preview version, and it's great for tanking. Storm Surge from Storm is really good, stunning everything around when it's triggered (only 5% though, but it ends up triggering quite often). That and the various shield attacks and you're good.
I should try Defense/Spirit to see as well, might be better for lasting long tanking with the life leech, but if you have like a Warfare/Spirit next to you, Storm Surge stunning your ennemies might be more useful
