Even after the nerfs, Illidan and Abathur combo is still more than a respectable threath especially if you then also stick a sprinkle of Uther, or Lt. Morales into the mix, you have a very highly volatile soup, which also hinges very heavily on that singular hero. The same of course also applies when Illidan is replaced with The Butcher.

Thus being able to pick heroes deliberatedly to shut down this kind of plays can mean getting a nearly automatic victory before the match even begins.

While definately more of a niche hero, Li Li absolutely excels at defusing the bomb described here.

The pitfall for any build obviously comes when you are using the build improperly. While the basic talent cooldowns are fast, a teamfight might not have the time to wait for your Blinding Wind to cooldown before it's all over.

This means you have to be fairly selective on when to use your E ability. The blinding effect is not indefinate, so even if you see Illidan, or Butcher in your view, you're still probably better off waiting for a little while until they make their move and dash in to engage you, or your team mate. While this might be obvious to most everyone, it is still of extreme importance to remember.

Another thing to keep in mind is your and your opponents positions. Your Blinding Wind is not targetable and it will focus on heroes, selecting the nearest ones. This means that your Illidan opponent might retain his vision if he's surrounded by the rest of his team. Remember, by default the Blinding Wind only reaches 2 of the enemy team.

When you're facing off against a team composition with 3 auto-attackers (Excluding supports and warriors that are primarily auto attack based.) you really might want to concider specking for the Mass Vortex instead to increase the targets rather than the duration up.

In a teamfight the significance is huge since your ability now reaches 4 of the enemy team instead of 1 very specific high priority target.

However without the longer, Lingering Blind, you really hope to at least place the opposing team in a rout after the duration is over if not a full on team wipe. The cooldown is too long for you to hope to cast it a second time during a fight, more than likely you are either chasing, or being chased by the opposing team.

Most battles are decided over not only by team compositions, but also by positioning. This means that anykind of roots, slows, or stuns you can apply on the enemy team on masse makes it so much easier for your team to either pick individual enemies out of the fight with a fast burst, or simply wipe them out with a highly effective Ring of Frost, or just by running stragglers over that try to run away to safety after a lost team fight.

Li Li doesn't really have great ways to zone, or Crowd Control the enemy team and thus applying slows to your already souped up Blinding Winds can easily be what it takes to win a fight, especially when it comes to tight corridor styled maps such as the Pirate Bay with little room to maneuver despite being a rather large map overall.

The Serpent Build in general has no obvious weaknesses, but similarily it has no specific strengths either. If this build seems optimal for the map, it kind of makes me wonder if there's a better support hero for the job.

That said it's still not like it was unviable, on the contrary. It fixes one of the largest major gripes people have with Li Li as a support. Untargetability. She's fully able to spam Q on a tanking warrior, while still topping up the health pool on a nearly full heatlh Kerrigan whom dives deep into the enemy team to wreak havock.

This build is at its best when you're against team compositions that aren't really here, nore there when it comes to damage sources. Some auto attack and some spell casters. Another optimal situation for this build is when the map objective specifically asks you to kill minions to achieve a goal. Since the serpent attacks bounce, it allows you to attack both the minions and the opposing teams heroes.

While your end screen statistics are almost guaranteed to be higher (Amount healed, siege damage and hero damage) when compared to the other builds on this guide, it is still good to keep in mind that your overall combat effectiveness is still going to be lower than usual with the other builds.

Some notes to keep in mind:
With the new patch, any summoned creatures on a blinded hero are also blinded. Thus I believe that if the host of your W water serpent is blinded, the serpent is also blinded and will not heal the host.

Especially at the late game, Li Li can become extremely mana hungry, eating it like cupcakes and thus while the Lingering Creature seems like a major buff, the cooldown on W is low enough as is and you cannot have more than 1 serpent out on another team member other than yourself at any given moment, making Lingering Creature nearly reduntant.