The Aronian-McShane endgame was incredible, 61...Qc5 probably the only move that leads to a win, 62...a3 certainly was and Luke found some really good defensive moves e.g. 65...Nf5 with little time.
Nobody really knew what was going on for most of the endgame, you're missing the end of the game though, it ended in a mate.
Oh, btw, the underpromotion was because 69...g8=Q lead to mate after Qh5 and Qb1.
It was a fitting way of finally taking down Garry Kasparov's unpublished Live Rating record, as Magnus Carlsen and Gawain Jones played a wild game. Jones sacrificed his queen for play, but Carlsen held fast and is now at 2857.4. Levon Aronian scored the next win, over Luke McShane in a thrilling endgame as he fought past four connected passed pawns