Blocking while not in active mode?

Are you able to block while not in active mode? I am asking as I tend to stay out of active mode when playing a caster to get the regen and was wondering if it was possible for me to block with my shield while in passive mode.

If not, is it recommended casters go into active mode if they get aggro? Also, if not, do shield skills work without being in active mode?

That's a good question...

I have been wondering this too. I still get Sentinel XP when in passive but I don't get MP regen in active so I hate to be in active mode.

No, you can't block in passive mode. You need to have your shield out