Since it announced a self-styled caliphate across Iraq and Syria last year, IS has become notorious for broadcasting its macabre tactics.
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The group's online network has taken advantage of social media's instant publishing power to circulate footage of mass killings and beheadings.
IS shot to global infamy in particular last year following the release of a series of English-language videos depicting the grisly executions of several Western hostages.
In November, US President Barack Obama referred to the group not as "masterminds" but rather "a bunch of killers with good social media."
But to maintain the media frenzy, IS has resorted to increasingly morbid and elaborate methods of killing.
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"The reason IS ups the ante is because they think people will be bored and they need or want to stay relevant," said Mia Bloom, a professor at Georgia State University.
Some of IS's more grisly ways of killing captives include firing rockets at them or tying them to ancient artefacts that the militants then blew up -- as happened in the historic Syrian town of Palmyra.
In a recent video from Iraq, it eschewed its usual before-and-after images of beheadings in favour of grisly footage showing the entire execution process.
The group has also claimed spectacular attacks abroad, including the coordinated assault in Paris that left 130 dead and the downing of a Russian airliner that killed all 224 people on board.
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"The graphic videos are attracting a personality type, people who want the real life 'Call of Duty,' people who have violent pasts and want to reinvent themselves," Bloom said, referring to a popular video game.
Indeed, in one recent video, IS child soldiers weave their way through a crumbling fortress to find and kill captives, in a scenario eerily similar to a video game.
The use of children in the propaganda is also a way of upping the stakes in terms of shock value.
"Children went from being observers of violence on the periphery, to actively involved and fully committed in the videos," said Bloom.
"This is un-paralleled."
IS uses this "ultra-violence" to impress its supporters, terrify its opponents and, importantly, to "project IS's message across the world", said analyst Charlie Winter.
Winter, who monitors militant activity online, said the group's propaganda juggles images of violence and portrayals of the "caliphate" as an Islamic utopia.
Among IS's online cheerleaders, broadcasts that feature new methods of killing are particularly "high-impact", he said.
But the threshold to excite supporters and intimidate enemies keeps rising, said Winter.
Whereas mass beheadings or shootings were "a rarity" last year, new incidents no longer spark the same global outcry.
"In the last few months, IS has continued to explore new depths of depravity -- killing people by dragging them to death behind SUVs, drowning them, burning them and so on," Winter told AFP.
"It has mainstreamed mass beheadings such that people are no longer shocked," he added.
The increasingly gruesome nature of IS's propaganda may also reflect the growing military pressure it has faced in Iraq and Syria, and a desire to continue projecting an image of power and relevance even as its output slows.
Analyst Aaron Zelin noted in a post for the International Centre for the Study of Radicalisation and Political Violence that IS's output has dropped off in recent months, as it has suffered several military losses.
Its media output this year peaked in the summer months, as the group scored victories in Syria's Palmyra and the western Iraqi city of Ramadi.
Output related to Syria peaked at 3,762 releases during the three-month period between June and August, but it fell to 2,750 releases in September-November, as Russia joined the fray with air raids in support of the Damascus government, he said.
Zelin said the drop could also be tied to the deaths of several prominent IS media operatives, including Junaid Hussain and Mohammed Emwazi, who were killed in US-led coalition air strikes in August and November respectively.
Hussain was a high-profile IS figure on Twitter, while Emwazi -- known as "Jihadi John" -- was the executioner who featured prominently in the group's videos of Western hostages.
But the drop-off also coincided with several setbacks for the group, which lost the Sunni Arab town of Baiji and the nearby refinery to Iraqi government forces in October.
The following month, Iraqi Kurdish forces backed by coalition strikes retook Sinjar, northwest of Baghdad, as anti-IS groups in northeast Syria dealt the militants a simultaneous defeat.
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