He murdered his uncle in order to take over the throne

One of the most famous and interesting facts about Alauddin Khilji is that He murdered his uncle and took over the throne. He fled Devagiri with a vast quantity of wealth after successfully conquering the city in 1296, including valuable metals, gems, silk goods, elephants, horses, and slaves. When Jalaluddin heard of Alauddin's victory, he traveled to Gwalior in the hopes that Alauddin would give him the booty there. Alauddin, however, marched with all the wealth straight to Kara.

Ahmad Chap, one of Jalaluddin's advisers, suggested intercepting Alauddin at Chanderi, but Jalaluddin trusted his nephew. In the hope that Alauddin would bring the wealth from Kara to Delhi, he left and headed back to Delhi. After arriving in Kara, Alauddin wrote the Sultan a letter of apology and expressed regret for any offense his opponents may have caused while he was away. He asked for a letter of pardon from the Sultan, which the Sultan sent right away by messengers. Messengers sent by Jalaluddin to Kara learned of Alauddin's military prowess and his preparations to overthrow the Sultan. Alauddin, however, held them and forbade them from contacting the Sultan.

Almas Beg, Alauddin's younger brother, persuaded Jalaluddin to travel to Kara to meet with him, claiming that Alauddin would commit suicide if the Sultan did not personally pardon him. The naive Jalaluddin led his forces into Kara. When he got close to Kara, he told Ahmad Chap to send his main force there by land while he, with with a smaller contingent of about 1,000 warriors, chose to cross the Ganges river. After feigning to greet the Sultan on July 20, 1296, Alauddin had Jalaluddin assassinated and proclaimed himself the new ruler.