Spawn bugs all the time, get healed by them and use Blood for blood for killing blows on heroes with less then 10% when the try to run away.
Ultimate setup is to go with a laning range dps like Zagara, Valla etc. that can escape when you got low health and need to return back with burrow for getting health. they normally help you with dps the one you figthing with too.
personal favorite, don´t know if its the best build, but it works for me. :)