Activated by casting Void Eruption. Twists your Shadowform with the powers of the Void, increasing spell damage you deal by 10%, and refreshing Mind Blast's cooldown.
Lasts 20 sec. Casting Devouring Plague increases the duration of Voidform by 2.5 sec.
Old: Each 25 Insanity spent during Voidform increases the duration of Voidform by 1.0 sec.
Patch 10.0.0 (2022-10-25): No longer gives [Mind Blast] an additional charge. Spending Insanity now increases Voidform's duration.
Hotfix (2020-11-17):Tentacles will now appear on the caster when using Voidform.
Patch 9.0.1 (2020-10-13): Now has a fixed duration and no longer drains Insanity, no longer grants additional Haste or reduces cooldown of Mind Blast, instead gives Mind Blast additional charge.
Patch 8.1.0 (2018-12-11): Now increases all spell damage by 20% (was 10%).
Patch 8.0.1 (2018-07-17): Now increases all spell damage by 10% (was 20% shadow damage). Cooldown on Mind Blast is now reduced by 1.5 seconds, down from 3.
Patch 7.1.5 (2017-01-10): Now increases Shadow damage by 20% (was 30%). No longer grants Lingering Insanity (now a separate talent).
Hotfix (2016-11-14):Voidform's Insanity drain now begins at 8 Insanity per second (down from 9), but will increase at a 10% faster rate
Developers' Notes: We want to reduce the maximum amount of time that [Surrender to Madness] can be maintained, without significantly impacting Shadow otherwise. Our intent in this hotfix is that it's still effective to use Surrender similarly to how it is currently used, but that its maximum potential in ideal situations is slightly less extreme.
Hotfix (2016-09-26):Voidform stacks no longer increase while Dispersion is active.
Developers' Notes: We would prefer that [Surrender to Madness] not be as dominant as it is, and that it can't be extended for quite so long. However, addressing this further would require significant changes to the spec beyond what we want to do in a tuning pass at this time. We will look for an opportunity to take a more comprehensive look at this issue in a future patch.
^WarcraftDevs on Twitter (2015-11-09). Retrieved on 2018-08-10. “@scotttboy1 Sounds like you may enjoy the fact that you're forced to speak Shath'yar - the language of the Old Gods - while in Voidform.”