“Let me explain what is happening to you,” Plagueis said. “The cells that make up all living things contain within them organelles known as
midi-chlorians. They are, in addition to being the basis for life, the elements that enable beings like me to perceive and use the Force. As the result
of a lifetime of study, I have learned how to manipulate midi-chlorians, and I have instructed the limited number you possess to return to their
source. In plain Basic, Veruna, I am killing you.”
Veruna’s face was losing color, and his breathing had slowed. “Bring … me back. I can still be … of service … to you …”
“But you are, Your Majesty. A celebrated ancient poet once said that every death lessened him, for he considered himself to be a brother to every
living being. I, on the other hand, have come to understand that every death I oversee nourishes and empowers me, for I am a true Sith.”
“No … better than … an Anzati.”
“The brain eaters? What does better than mean to those of us who have passed beyond notions of good and evil? Are you better than Bon
Tapalo? Are you better than Queen Padmé Amidala? I am the only one 􀀲t to answer the question. Better are those who do my bidding.” Plagueis
placed his hand atop Veruna’s. “I’ll remain with you for a while as you meld with the Force. But at some point, I will have to leave you at the
threshold to continue on your own.”
“Don’t do this … Damask. Please …”
“I am Darth Plagueis, Veruna. Your shepherd.”
As life left Veruna’s body, the path he and Plagueis followed wound deeper into darkness and absence. Then Plagueis stopped, overcome by a
sudden sense that he had already seen and traveled this path."
Veruna instantly loses strength here. All he can do is weakly plead as Plagueis kills him.
Palpatine also notes Plagueis got sloppy and decided to gloat rather than making a quick end, like Maul did to his prey. "Had Plagueis done so before killing Veruna? Had he felt compelled to come out from behind his mask? To be honest?" Palpatine comments on 'drawing out the moment' instead of making a quick end.
The best part, is it doesn't matter. Zannah is a weakling next to these two and Bane's only a factor do the orbalisks. Both can make sure neither knows their intentions and even if Plagueis cannot instantly murder them? Well, it's simple: He just uses the technique while dueling them unless you make the laughable argument Bane can steam roll them in saber combat.
It's a quick and easy fight. Zannah tries that nonsense with the tentacles, Plagueis hits her with a force wave that atomizes her, or snaps his fingers and bursts apart a vessel in her brain while she can't defend. Hell, what stops a force shield form blocking those, since you're so fond of that defense?
Palpatine or Plagueis kill Bane pretty easily. All Plagueis has to do is murder a single orbalisk in the force. Hell, Palpatine can do that with force lightning at worst.