Originally Posted by Reidan
did you even read what you posted? bloodthirster is the largest increase to death lotus you can get from an item, unless you have like 5 and are comparing them to a magic pen item
There's an ongoing debate about whether it's better to simply save the money and use it to stack BF swords which are more far more cost effective for AD than bloodthirster unless you can get (and keep) the bloodthirster fully charged.
The flip side to the argument is that 1-2 bloodthirsters give Kat great staying power while laning and pushing, and without the lifesteal for longevity Kat has to spend extra money on health pots, or extra time blue pilling back to base when she otherwise would not have.
I have not seen anyone conclusively say one way or the other that one is better. I'll usually start with a BF sword, and depending on how frequently I'm dying (usually I put up great K/D ratios with Kat), then I'll upgrade it if I don't see myself dying in the near future.
When it comes to the original rune question, the best suggestion is really just to look up Furor's profile, and copy-> paste his runebook. If I remember right, he does go with magic pen in reds, I think dodge in yellows, and cd reduction in blues. I forget which his quints were, but I think health or dodge (at work and can't check atm).
edit: and yeah, katarina IS lotus. It defines her. It is her saving grace, her one purpose. For anyone to say that lotus is underwhelming or not a significant source of damage, something must be going wrong.