Good place to solo for a 28 Troll SK?
 

Thinking an undead dungeon would be good for the xp bonus and Ward Undead.

try unrest

Having less downtime by fear kitting may net a better xp pay off.

Off the top of my head:
Lake of Ill Omen
Giants in FM
Guards Valon and Colin in WC

I've been soloing HighKeep guards since level 27 as a Human Monk. Experience modifier is 160% highest in the game as far as I know. Guards drop a fine steel sword every time. I believe the vendor I sell to now that I am kos will sell to you as well. He's in a room behind Guard Dister.

You can feign death past the guards at the entrance. Then you should be able to kill Guard Blayle, Lancel, Ruan, Dister, Drugan, and Folton. They are on 18 minute timers, if you can kill faster than they at level 28 you are doing quite well. Some feign death splitting might be neccesary, Lancel/Blayle will need split. Also, Ruan will need split from Boshinko.

If you do plan on going here, I can help you get started.

Thanks for the tips - much appreciated. Can't feign split yet since SK's don't get feign until level 30.

Oh sorry, didn't realize that. Giant Skeletons perhaps in Rathe Mountains. I think they are level 22-30.

Ward undead is a waste of mana... Inefficient.

Sisters on sister island are perfect for you. Not like you will ever be welcome in Kelethin anyway.

That

Also, you can fear kite giant skels in rathe mountains or the various undead in LoIO...or the giants in the WW Giant Fort... But Sister island WILL be better $$.

Thanks for the tips. I ended up in Rathe Mtns and am absolutely owning the Giant Skellies.

You're right about Ward Undead - not worth it.

But what IS nice is Spook the Dead (Undead-only Fear with a 2 second cast, for 10 mana). I can keep those guys running from me (snared) all day while me and my pet are destroying them.