I'd like to add you can also do the daily/weekly HW and SB hunts to get Centurio seals. These seals can be exchanged for i310 gears at Rhalgr Reach, near the hunt board. I think there are i330 gears (was previously creation tome gear) as well but I'm not in game to check. This should help boost your ilevel to unlock Skalla and more stuff for your tome/gear farming.