The game is great and has been challenging but not too hard...UNTIL...I got the Ruins Sentinel bosses (those 3 b*stards with those long weapons they can spin around). I am getting owned over and over again even using the phantom you can call to help. I'm playing as a sorcerer too weak to even carry a shield (though very strong spells). Trying to dodge that first sentinel on that small ledge with my weak HP and weak armor and no shield is not a good place to be. Has anyone else beat these guys and what did you do???
You have to kill each one quickly, preferably on that small ledge you start on. It's the only time you get to take one of them on solo. You have to deal damage fast and be able to either dodge or block their attacks reliably. Taking on all three at once, even with two additional players, is untenable because they'll often gang up on you all one at a time.
As your a sorcerer, you're best bet is summon someone and let them draw the boss's attention while you pound them with spells. That or you step away from this area for a while and level up a bunch. I didn't beat this boss until I was around... level 74, I think? And even then, it was still a close battle.