So I have only been playing HotS for a little while now but I enjoy it a lot and the first Hero I bought was Lili. I tried building her full support maxing all of her healing talents but I found she was just not able to heal enough to compensate for complete lack of damage.

I tried this build several times and I have had great success with it. Her healing output is still very nice with Mending Serpent and your Q. She does't seem to get super low her self either due to Serpent Sidekick and with the additional time added from Timeless creature the Serpent lasts longer than the cooldown so it is ready to be cast again 2 sec before it wears off.

*Disclaimer* I am certainly no pro at HotS and this is my first guide I've made so its a bit rudimentary but I really enjoy playing Lili with this build mostly cause low hp assassins who try to burst you find that you have more damage than they expected( especially if Water Dragon is up) and they usually get shut down and your still able to support and keep your team healthy.