According to Principal Game Designer Mike Donais, if a minion's deathrattle damages other minion(s) and has Poisonous through Adapt / Plague Scientist combo, it will work.
Before this bug was fixed, only the following could happen:
A Fiery Bat gets the Poison Spit adaptation from Crackling Razormaw. Its deathrattle is triggered by Feign Death, and instantly destroys the minion it damages. Later the Fiery Bat dies and the deathrattle triggers again, but this time the damaged minion does survive.
After the bugfix arrives with an upcoming patch, if the Fiery Bat dies with Poison Spit adaptation from Crackling Razormaw, it will destroy the minion that was pinged by its deathrattle, no matter what was that.
I found a Dev response in the Mage card leak's Reddit post:
https://www.reddit.com/r/hearthstone/comments/6ojed1/new_legendary_mage_leaked_a_french_ad_show_the/dki129m/
According to Principal Game Designer Mike Donais, if a minion's deathrattle damages other minion(s) and has Poisonous through Adapt / Plague Scientist combo, it will work.
Before this bug was fixed, only the following could happen:
A Fiery Bat gets the Poison Spit adaptation from Crackling Razormaw. Its deathrattle is triggered by Feign Death, and instantly destroys the minion it damages. Later the Fiery Bat dies and the deathrattle triggers again, but this time the damaged minion does survive.
After the bugfix arrives with an upcoming patch, if the Fiery Bat dies with Poison Spit adaptation from Crackling Razormaw, it will destroy the minion that was pinged by its deathrattle, no matter what was that.
<Waiting for sinking down in the recent threads page>
Bumpers.
Whoa, this opens up a lot of possibilities for our new Rogue friend, we will finally be able to fend of that pw pest.
Tentacle of N'Zoth will be a powercreep with Plague Scientist and this bugfix.
Sergeant Sally's time to shine? Perhaps a razorpetal will be a convenient way to kill her on demand