Shauku, Endbringer - Group Kill (EDH / Commander)

First death, then Shauku...

Shauku, also known as the Endbringer, was an ancient vampire of Femeref descent. She was a dangerous creature, capable of draining the life from all other beings to assist her undead existence. She was also an isolationist whose tone was generally curt and threatening, even her wisdom was abrasive. Shauku considered herself masterless and free to do what ever she wanted, especially in terms of life and death. Her past is shrouded in mystery, but it is said that she was once tried to lure the evil mage Johan into her service, but failed.

She reigned in Aku within the Uuserk Marshes and had several minions, mundungu and other servants that did her bidding throughout Jamuraa. With their aid she also maintained an ancient and unpleasant library. Those who wished to read the texts found that they had to study under her for a year, and had to donate blood to her regularly. Shauku used the blood to divine much about the students, and while they could leave Shauku's home in one piece, she would always own and control a piece of them.

During the Mirage Wars she was approached by Kaervek who wanted her to aid him in his conquest of Jamuraa, but she declined. Being a xenophobe, Shauku disliked strangers and crowds and was underwhelmed by the notion of being involved in an open conflict. She was actually more savvy about the powers of her opponents than Kaervek and knew better than to get involved.

A cult surrounding Shauku appears to have been active during the time of the Prophecy War, but it is unknown whether the cultists simply regarded her with reverence or if they were actually in her service.

More info on Shauku:

In the fight between the evil mage Johan and Jedit, Johan manages to escape in the Western Wastes. There, he has a vision sent by the mysterious Shauku, who invites Johan to her library, where she has tomes detailing the tigermen of Efrava. After a travel to Buzzard's Bay, Johan learns the location of Shauku's castle, deep in the pinelands of Arboria, in south-western Jamuraa.

When Johan and his entourage reach Shauku's castle, which is little more than a ruin, Johan finds a book on the Efravans written in an unknown language inside the castle. Shauku, with the excuse of casting a translating spell, instead casts a commanding enchantment on Johan, binding the wizard to her will. Sensing something strange with his host, Johan follows Shauku into the castle bowels, where he finds a huge cavern with a Cosmic Horror imprisoned (see note* below). Near it stands a vampire; the real form of Shauku, who reveals to Johan that her library was a sham, devised only to bring the mage to her to enslave him and rule all of Jamuraa as the real power behind the Tirras emperor. Johan is then trapped in an amber prison near the horror.

Meanwhile, Jedit is in search for Johan, and in Arboria, Jedit and his party befriend the pinefolk, who have no love for Shauku and her Akron Legionnaires. The group manages to infiltrate the dungeons of Shauku's castle, where they too find the cosmic horror and Johan's prison. The Robaran Mercenaries that are following Jedit intend to free the cosmic horror, to let it have its revenge against Shauku, but before they can do it, Shauku and her legionnaires' attack. During the fight, Adira inadvertently frees Johan from his prison who, having read the mind of the horror and its intention of calling a Falling Star down on the castle, promptly flees the fight. After Jedit incapacitates Shauku, the Robarans and the pinefolk quickly follow Johan's example, escaping the castle just as the falling star strikes, destroying Shauku's castle.

Note*: A number of kobolds were summoned by Shauku (whom they called the Yellow Lady) to tend the fires guarding the Cosmic Horror imprisoned in her castle.

And even some more info:

Until around 3300 AR (the Dominarian timeline is in AR: Argivian Reckoning, with year 0 starting with the birth of Urza), Arboria was stalked by the Akron Legionnaires, who kidnapped the pinefolk to feed them to their master, the vampire Shauku, who resided in a castle in ruin deep in the forest. Another horror known to feed on the unwary traveller of the forest was the Floral Spuzzem, which was in reality one of the first inhabitants of Jamuraa cursed by the Cosmic Horror imprisoned in Shauku's castle. After the intervention of Jedit Ojanen, Adira Strongheart and her Circle of Seven, the vampire's castle was destroyed, ending the menace of the Akron Legionnaires and the Spuzzem, even if Shauku would later resurface.

Sources:
https://mtg.fandom.com/wiki/Shauku
https://mtg.fandom.com/wiki/Jedit_(novel)
https://mtg.fandom.com/wiki/Kobold

"Since I cannot stop death, I choose to stop life."