Mother Shahraz's Seduction - Legendary Question

[NoID6]

Hello,
I was lucky enough to have my legendary drop in Heroic-Maw and was just curious about it's Equip ability.

Equip: When you enter Voidform, every 7 sec of remaining duration on Lingering Insanity grants you a stack of Voidform

I'm not entirely sure what a "Stack" of Voidform is.
Any clarification would be greatly appreciated.

Side note: I've noticed (a possible bug) where i'm having to cast Void Eruption twice before being able to cast Void Bolt. Is this the stack of Voidform from the legendary or are other spriests also running into this?

[Dawnrage]

Every second you are in voidform, you gain a stack of the buff "Voidform" which increases your haste by 1% (I've read it's a little more than that since it's multiplicative with your haste too).

What the legendary does is make it so that if you have, say, 42 seconds left on Lingering Insanity when you next enter voidform, you would gain 42/7 = 6 stacks of Voidform, meaning you would start Voidform with 6% more haste (and stacks). These stacks are significant also because the drain isn't factored into the stacks, so it's not like your insanity is draining at the rate of which you were 6 stacks into voidform, but you would have 6 stacks and voidform would start it's drain from 1.

Essentially, having the legendary means you would have a longer laster voidform from having higher haste during it, and ending voidform with more lingering insanity stacks than you would without it.

As for the bug, never heard of it, but if it's related to wearing the legendary and you are seeing this when you use it as opposed to when you don't, you might want to submit a bug report.

[NoID6]

Thanks, that actually answers my question extremely well.
I wasn't noticing the stacks of Voidform buff until now.
Feel kinda silly posting this now.

But thank you!