When Li Li's Cloud Serpent (W) is cast on Zagara and if Zagara has taken the Medusa Blades (Level 4, second talent), does the Cloud Serpent attack to multiple targets?
If Cloud Serpent is cast on Tychus, how often does the serpent attack?
From my own experience, I have found that the cloud serpent is independent of the attacking speed or the number of targets that the buff-holder himself can attack. It is just like a minion that is bound to the guy that is buffed with it and attacks the target that the "owner" is attacking with its own speed.
For the cloud serpent to be able to attack multiple targets (in a way) you can choose a certain skill that I cannot remember just now.
Again: this is only my experience from playing her today for a few hours, so I don't have another reference for this now.