Spirit Shrouds basicalyl allow you to turn into a Monster. They vary in classes from a Wizard, Warrior, Rogue, Berserker, Cleric, Enchanter. However every one of them is really watered down. Also you can select level lower then you. It works well if you want to hunt with people lower then you (although the exp gain is pretty slim if you lower your level for obvious reasons). You also can unlock more shrouds, however it takes a terribly long time to do.
Something you didn't mention is what level your charactor is? The way the game is now there are very few low level players in the game. It is not uncommon to do a /who all 25 30 and not find more then 10 to 15 people on-line (let alone people LFG).
LDON is pretty much a dead expansion (sadly enough) because it was (and still is) good exp for lower levels. It seems like after lvl 50 exp is now pitiful in LDON. Rumors circulate that LDON got nerfed after Gates came out, although Sony denys it. But I do know I was getting double the amount of exp on my 55 warrior (at the time) then I did after god came out.
Pretty much every expansion since LDON has been high level content. GOD starts about lvl 50. Omens of War has some lvl 45ish content, although every Omen of War mob is underconned (everything seems to proc some sort of insane spell when it melees you).
Depths of Darkhollow zones are 50+, however you can do monster missions at any level. This expansion started out very nice until soe nerfed it, nerfed it again, nerfed it again, and one more final nerf. Started off Monster missions gave about 1 AA worth of exp. Then they nerfed it to where you got half that amount of exp. Then they nerfed it so that certain missions gave alot less exp depending on difficulty. Then the final nerf was to make monster missions more difficult to complete. When expansion first came out that is all people did, however after the nerfs DODH has become a fairly worthless expansion (this is of course my opinon). I still see people do the Butcher Block monster mission every so often. Alot of people, including myself feel like it was a big scam. MAde a expansion that was great. Then after people buy it up they nerf it.
I can't tell you much about Prophecy of Ro as I don't own it. You don't get it with titanium and once again its pretty much high level content. It does have some new Monster Missions which I understand give great exp. I seem people do them all the time. I see people do that DAin mission just about all day.
Anyways hope I have answered your questions a little bit.
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Hi