Herald Of Plague nearly useless

I very much like the idea of this herald and I played around with it. Its only really good if youre hard specialized into poison and can inflict it reliably. Herald skills are meant for helping to clear mobs, and poison in general is really slow. It is not as good as other herald skills, it needs something more??

It needs either to be more supported by gems like bursting plague, or an innate chance to poison with hits, or being able to inflict more poisons on enemies. something more to justify its use