After 7 draws, game 8 is the first decisive game of the match. Karjakin won with black after an exciting game that saw Carlsen taking a lot of risks. There were many critical moves, espcially in the endgame when Carlsen had the chance to save the game after Karjakin missing a tactic during time trouble.
The first critical decision was in move 24, Carlsen played bxc4 instead of Rxc4 creating an unbalanced structure and ultimately giving both a and c pawns later.
The first pawn was sacrificed in the following position in move 31, Carlsen played h3. Instead he could have taken Rxd7 giving the rook for two knights, and Karjakin capturing the e and c pawns with checks leading to an equal position and likely perpetual.
The second pawn was sacrificed in move 35, when Carlsen played c5 to get an attack on the king.
Under attack in time pressure, Karjakin in move 37 played Qd3 allowing Carlsen to play Nxe6 and his queen taking the pawns around the black king. Instead Qa4 would give Karjakin a clear advantage with an extra pawn.
Carlsen returned the favor in move 44 by playing Qc6 instead of trying to hold the draw with Qg6+.
After a sequence of challenging moves, the following position was reached in move 50, Carlsen had the chance to play Qb7+ fighting for the draw, but instead blundered with Qe6 followed by another blunder h4.