Spiders Expertise should be prioritized, other than that she pretty much is a 50 extra skill point hero, especially for lich. Personally my lvl40 build would look like this: 7 in spiders expertise and spider web, 3 in speed hatching, 5 in mother of spiders and 1 in venom explosion.
This is pretty close to what i actually run on my 40 rose with maxed ability points. i'm currently trying toxic touch over web just to see how much damage it does, but i agree with the above. For lich, rose is the first 50 skill hero to go for, and should have maxed command as well. Her spiderlings are really freaking strong with the above build. like stupid strong, so im really not sure what to max second since there are multiple good options. It probably makes sense just to go for web since its high impact for all races, but as stated, rose is a 50 skill hero, so you should almost always just have the key abilities near max as you level her.
-You should max magic on Vega then Tiadrin if applicable before moving on to Rose. It really only affects her toxic touch which does a ton of damage, but its not as important as Vega heal etc.