I almost always buy this item, but given the many complaints from AP champs, an interesting change can be made.
The passive no longer triggers when below 30% hp. Instead, you can activate it at any time, but it still has the same 90 sec cd.
What if you forget to use the active? How many times have you forgotten to use the Zhonyas active? Like almost once a game, right? But you remember to use it after that one blunder.
You randomly step on a Teemo shroom, but might be like "dont pop" to your hexdrinker passive. Now you can control it.
Are you about to fight Cho? Better pop the active early because when you come close to 30% hp, the passive currently is not even going to save you from the true damage execute.
If Cho does not have his ult, he can silence you and you will not be able to use the active.
I'm about to take heavy magic damage, so I pop the active. The enemy AP champ can then decide to save his ult and look for a play after the shield expires.
There is a Garen that has gone MIA, but you are not afraid of him because you bought a Hexdrinker. Well then you better activate it before you face check that brush.
Say you are fighting an AD champ and just want the lifesteal, spell vamp, and attack speed, well now you can just pop the active. But beware of that Leblanc that is going to kill you in a few seconds because you wasted your shield.
Although I think both Hexdrinker and Maw should have the active, we can also consider having Hexdrinker keep the passive and it upgrades to an active upon completing Maw.