Board Thread:League of Legends discussion/@comment-25305985-20140814225215/@comment-1330314-20140814233536

If your question is "does the 8% current health damage get dealt with every tick of ?" then no, as BotRK's passive is an on-hit effect, and so only gets applied through autoattacks (and only once per autoattack). However, since every basic attack will deal 8% of your opponent's current health in physical damage, you can still build this on, go full AP alongside that and still have the passive work fine.