User blog comment:Pualover/Overlord Power Level/@comment-94.219.219.78-20150921153141/@comment-24558666-20151008201201

Well, liches who are lvl 30 are said to be second strongest undead spawn at Katze plains(and same as with Death Knight, only one Lich was spawned at Katze plains based on wiki). So they should be under lvl 30.