Hi there!
Just got into Shadowmirk and that eye is really killing me (haha). How do I get through the portcullis and out of the room with all the columns?
Do I need to solve the puzzle with the candelabra first?
If your character is not really advanced yet, don't expect to kill that eye, or at least not to do it without lots of run, hide, heal, and come back tactics. You can go there later in the game when you get some levels up. Those eyes aren't an easy thing. Currently I'm around level 15 and they are still a challenge. Not a hard one, but their magic is strong, so it all depends on your luck resisting it.
Anyway, be sure to advance your char in the combat skills you are going to use, and do it wisely. If you focus too much in secondary things as Cartography or Alchemy, you will find you got a character that is not very useful in combat, or that is a bit harder to play. I focused on Swords and Archery (18 and 20 right now) and I can kill thinks fairly easy.
And a small advice... if you go to a new map and find something that makes you say "oh wow, what's that", you can try killing it, but if you find you barely hit it, and that it hits you way too much, it's time to say "ok, this is NOT for me right now, be back later".