The first adventure pack is for lvl 34ish players and is mostly abandoned now due to lack of interest. Splitpaw saga is for lvl 20+ as alot of it is instanced zones, however its really not used alot either. I can tell you the Splitpaw Saga is somewhat soloable, but the SOLO encounters are really difficult for their levels. They are usually solo encounters with a bunch of various casters in them. When I had my conjuror I couldn't even solo a solo encounter in there, however my paladin can if I use my heals carefully.
Personally I wouldn't fool with either adventure pack, but thats just my opinion. Its rare to find any pickup groups in either anymore.
And like the last post said you can't kill anything in DOF until 45+. I have heard of lower levels dodgeing KOS mobs and getting some discovery exp, but that doesn't seem like a worthwhile reason to buy a expansion.
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Hi