Dale Yorkes, while helping Jonah to heal Victor Stein, managed to steal a vial of Jonah's Serum.. Dale and his wife Stacey conducted several analysis on the serum to assess its properties and eventually came to the conclusion that they could use it to create another serum, which could be fatal to Jonah.
Dale and Stacey Yorkes were eventually able to create the serum they had in mind. They informed PRIDE of this achievement and asked Leslie Dean to arrange for them to access the PRIDE Construction Site, as they knew that the living beings in the hole dug at the site were related to Jonah. Once on the site, Dale and Stacey performed a biopsy using a Synnergy Drone, and injected the serum in the sample. Much to their enthusiasm, it triggered necrosis, indicating that their serum was working. However, their actions also caused an earthquake as it had disturbed the beings they had biopsied.
- "Who brings poison to a bon voyage party?"
- ―Stacey Yorkes
With their trial being successful, Dale and Stacey Yorkes manufactured several doses of the serum, intending to use it against Jonah's Ship when Jonah would attempt to leave Earth should he be a threat to anyone. Indeed, during the Battle at the PRIDE Construction Site, the Yorkeses decided to use the serum as the ship's launch was causing an earthquake. Using specialized guns, Dale and Stacey fired several doses at the ship's shell and, combined with the effects of the Anti-Gravity Device created by Janet and Victor Stein, it was enough to stop the spaceship and destroy it.
In the ensuing confrontation, as Jonah violently attacked both PRIDE and the Runaways, the remaining doses of serum were scattered on the site. One of them was found by Nico Minoru, who sought revenge for the murder of her sister Amy. Minoru broke a vial with the Staff of One and soaked the edge of the artifact with the spilled serum. She then stabbed Jonah from behind with the Staff of One, enabling the serum to directly affect Jonah. With his host body being damaged and his light form being hurt by the serum, Jonah was forced to leave and to seek another host.
- "It's turning black! Necrosis!"
- ―Stacey Yorkes
Although derived from Jonah's regenerating serum, the Anti-Gibborim serum has completely adverse effects. Indeed, when put in contact with Gibborim tissue, it triggers an irreversible necrosis, causing the usually white and glowing tissue to turn black. The serum was powerful enough to cause the destruction of Jonah's spaceship.
In chronological order: