Tier 1: Conjurer's Pursuit - You will need massive amount of mana later.
Tier 2: Definitively Mass Vortex - Blinding and later slowing 4 targets instead of 2 is insanely IMBA
Tier 3: Pitch Perfect - You will need massive amount of mana later.
Tier 4: Water Dragon - At the moment its impressive spell,70% slow for 4 seconds is just hilarious and on level 20 You will have 15sec cooldown if You keep your fast feet active...
Tier 5: Hindering Winds - Slowing 4 targets over and over again is impressive for both chasing or escaping...
Tier 6: Herbal Cleanse - Also very IMBA talent, always make target that get focused faster so he can easily escape+dispelling everything bad from them so they can freely run back
Tier 7: Kung Fu Hustle - This is why You need massive amount of mana! If You get to this point of a game You should literally provide free win to your team because You become INSANE support/tank, You should always try to be around front or a bit back so You don't get nuked down but try to jump into AoE spells so You have your Fast Feed(Passive) activated as long as You. That way You can spam heal constantly that heals for good amount+gives speed and dispell negative effects, spam Blinding Wind which makes 4 out of 5 enemies slowed+miss 2 attacks and as soon as they finally hit their target You can cast your Blinding Wind again making them miss again... You can even feel free to tank if Your tank lacks some help or You don't have a tank in team for some reason.

Conclusion: Level 20 Li Li is most imbalanced support so far (My opinion)