While Kantal has always had a killer instinct, he was not always in the lofty position he now holds. He was once part of a simple eight-man science team responsible for laying the seeds of militarization and indoctrination across the galaxy that later began the Cardiff Order.
While his colleagues defected, Krell remained loyal to the Ubiar. He used the weeks his colleagues spent deliberating to make contact with the Ubiar and undergo the Trials required to gain the power to take down his former colleagues. When it came time to strike, his team had intercepted his communications and covertly fled to the ocean paradise now known as Ahch-To.
While the Order sought to undermine the Ubiar invasion, Kantal did his very best to stop them at every turn. They eventually began training students to combat Krell: all of which died or came to join his cause.
That was until they began training their star pupil, Markus Kemp, who seemed to be their first prospect powerful enough to stop Kantal. However, Kemp eventually was seduced like all the others, giving Kantal the opportunity to open a wormhole on Bastzuda and start the Ubiar Invasion.