The Mahabharata settles its debts by assignment. Bhima has sworn to kill Duhshasana and Duryodhana and does. Arjuna is set against Karna and against Jayadratha. Dhrishtadyumna is born to kill Drona. And Shakuni, the uncle of Gandhara whose loaded dice began the ruin, is left to Sahadeva, who had sworn in the hall to kill him. On the eighteenth day Sahadeva does it, and he also kills Shakuni's son Uluka, the messenger who had carried Duryodhana's taunts to the Pandava camp on the eve of the war.
The pairing is deliberate. The quietest of the brothers is given the man whose weapon was not a weapon at all. Shakuni fights conventionally at the end and dies conventionally, which the poem seems to enjoy: the trickster is finally killed in a straight engagement by the brother nobody watched.
Later regional and popular tradition has enlarged Shakuni considerably, giving him a grievance of his own, the destruction of his family by the Kuru house, and dice cut from his father's bones so that they would always obey him. Those details are not in the Sanskrit epic, which supplies him with no motive beyond partisanship for his nephew and no explanation of his skill. They are worth naming as later growth rather than as text, because a great deal of what people now assume about the dice game comes from them.
The thread that began with a rigged throw therefore ends with two deaths, and the epic notes them briefly and moves on.