WARNING: The following contains spoilers for X-Force #10 by Benjamin Percy, Joshua Cassara, Guru-eFX and Joe Caramagna, on sale now
Ever since the X-Men relocated to the island of Krakoa, they've found themselves facing more threats and problems than usual, which is really saying something for Marvel's mutants. They all stemming from the various powers across the globe that seek to keep mutants at bay.
And now, the latest of those threats is directly the fault of an iconic X-Man. In X-Force #10, Beast just realized that his tinkering with the teleflronics of Terra Verde became the plant creatures that killed its populace, leading Jean Grey to tear into him and leave X-Force out of for the actions of one of her oldest friends.
The nation of Terra Verde was attempting to develop telefloronics -- a biotech that could potentially transform humanity into a new form -- but hit a major wall in their research while Krakoa came onto the global scene. Krakoa promised many of the same things Terra Verde had been developing and was actually able to deliver on the promise, which effectively undercut Terra Verde's place in the world.
As Terra Verede's telefloronic people attempted to accept the Krakoan deal to save their nation, the President's son Hadwin - a leading member of the Telefloronics group - staged his kidnapping in an attempt to set off a conflict. Beast secretly destroyed the Teleflornics lab when he discovered this and kept it from his teammates in the name of deniability. To deal with the threat of Hadwin and keep his secrets, Beast reprogrammed the telefloronic cells within his body to identify natural processes as an infection. This effectively left Hadwin's brain dead and ensured peace between Krakoa and Terra Verde. However, Beast's manipulations were too effective, and it led to a major mutation in the Teleflornics.
By manipulating the genetics of the plant, Beast didn't anticipate the symbiotic "give-and-take" between the biotech and the human mind. With no mind to contend with, the plants became dominant and mutated the body into a plant-hybrid. Soon, this new natural form of life had spread and infested the entire country, completely overtaking Terra Verde and turning it into essentially an evil Krakoa. This also caused the deaths of every citizen in the nation, either as sacrificial fuel for the growing life or as human-plant hybrids like Hadwin.
When X-Force went to investigate the nation, they were attacked by the plant-creatures and quickly picked off, with Quentin Quire being killed and Wolverine being prepared as a sacrifice. Terra Verde quickly proves to be a major threat, and it is all Beast's fault.
In X-Force #10, Beast tries to get the situation under control and argues that this can be seen as a good thing, an opportunity that Krakoa can use as training to better prepare for future conflicts. However, Jean reads his mind and learns the full extent of his involvement with the Telefloronics. This sends Jean into a fury, enraged that Beast would keep secrets from his teammates and fellow mutants. Beliving that trust in one another is the key to mutants on Krakoa surviving a very dangerous world, Jean forces Beast to psychically experience the deaths of an entire nation as they were absorbed into the telefloronics.
As she departed alongside Sage and joined Black Tom to save her teammates, Jean makes sure to. remind Beast that they have to hold each other accountable for their actions; otherwise, they risk becoming something far worse then what Krakoa is meant to be. Together, Jean, Sage and Black Tom are able to break down the more aggressive aspects of the teleflronics, again manipulating their DNA and leaving a host of unconscious human-plant hybrids that may continue to live on, potentially becoming a threat to Krakoa again down the line.
This isn't the first time Beast has tried to "fix" something only to make matters far worse. His early experimentations to hide his mutant-powers actually led to the acceleration of his X-Gene and his current beastly form. He was responsible for the original five X-Men being trapped outside their proper place in the timeline, almost causing irrevocable damage to all of reality as a result.
But this newest mistake likely cost thousands of lives, simply because of his belief that he was in the right and that no one else would understand. His mistake not only cost those lives but seemingly the trust and respect of Jean Grey as well, with his fellow founding X-Man quitting X-Force out of disgust over Beast's actions. With what he unleashed on Terra Verde, Hank McCoy destroyed one country, and his actions here show that he's a central figure to Krakoa's moral rot, too.