Yeah, stamina/mana seems to be perpectually stuck at 100. Maybe that can be increased by items? But unless it can be increased by A LOT I'll ultimately end up favouring other things. That also really means the mana/stamina costs on spells are, atm, basically a percentile. Devour costing 65 is literally 65% of your stamina lol. Shield Wall 10 stamina per block? That's 10 blocks before your out. In the Giantbomb quicklook it seemed that holding shield wall was also not letting stamina regenerate so, unless proven otherwise, I'm assuming all sustained stop regeneration. Though that might entirely be to the double large V held-sustained skills instead of stuff like blizzard. I mean I doubt stealth stops your stamina regeneration while your stealthed.
Anyway, with that in mind, gonna need to be able to attack between guard building to keep stamina going. I think SnB tanks are gonna definitely have to get into a rhythm of building guard then auto-attacking to be able to shield wall again before all the guard is gone. Course it also seemed to semi-stun enemies (or caused to em reel from the block) so that might give time, at least in a 1v1 or 2v1 to block the attacks, and get a hit in before blocking again. Makes me wonder how hard it'll be with block and attack skill on 2H.
-edit-
This also kinda makes my point for me from earlier about taking a lot of dmg skills vs being more versatile. Really going to just tear through stamina/mana to quickly if you don't think about it to carefully. One reason tanks keep failing at tanking in DAMP streams... to busy using attack skills and not deflecting. It's a limited resource for a reason. 