This happened after her fight with Ekko at the bridge and after the explosion that severely injured her. She almost died, temporarily loosing sight in her right eye and almost loosing her right arm. However, Singed (Idk his name but he's the evil doctor and the creator of shimmer) was able to save her by using a new shimmer product that he made: Nano-Shimmer, or NS, a mixture of Nanotech and Shimmer.

The NS can be directly put on a wound like Nanotech, but when it comes to broken bones and injuries that are so bad that amputation of the injured limb would be the only option, the NS would have to be surgically implanted in the injured limb's main joint (Ex: the shoulder blade). NS healing takes a long time to kick in, but it can be quickened by adding more Nanotech or Shimmer, however adding more Shimmer would make the heal progress a lot more painful than adding more Nanotech.

In Jinx's case, she had to, unfortunately, endure the extremely painful experience since Singed used Shimmer instead of Nanotech since he has more of the purple drug in supply then the NT. He's also a sick bastard sooooooo.... Yeah.

Anyways, because of the injures and agony she sustained, Jinx falls into a coma for the rest of the day. (Like seriously, Jinx couldn't possibly get back up after enduring that agonizing experience with the Shimmer injections. The poor girl must've lost consciousness afterwards.)

Scourge stays by her bedside, hoping that his sister figure would wake up soon. After seeing the desperation in the hedgehog's eyes and knowing about his powers, Singed wanted to... test something out. He wanted to know if it is possible for a lombax to gain the same electrokinesis as Scourge. So he walks up to Scourge and tells him that Jinx would most likely wake up the next morning, however she needs a blood transfusion because she seemingly lost a lot of blood, despite her ACTUALLY not needing it because most of her wounds were burns and burns rarely bleed.

Scourge knows this, however he immediately agrees because he wants Jinx to be OK. Luckily, Scourge had the same blood type as Jinx so it's safe to transfer his blood to her.

After that, the blood was hooked up to her and the mobian blood reacts to the shimmer in her blood therefore giving her some cool purple electrokinesis. (because why not?)

However, Jinx, being Jinx, rather uses her bombs and big death guns instead of her new powers. She only uses them for intimidation and torture. But due to Scourge's powers being connected to Hextech, Jinx's powers could charge up her rocket launcher "Fishbones", which was powered by Hextech, therefore completely destroying the council's tower. (Good! They're corrupted douche bags anyway!)

Also fun fact, when fighting Rivet, Jinx was brutally smashing the shit out of her mostly because she's faster than her. Remember, this is Scourge's blood we're talking about, and Scourge's real name is Sonic, and you know how fast Sonic is.