Frostmourne captured his first graded stakes with authority when he stormed down the stretch under Irad Ortiz Jr. to capture the Penn Mile (G2) by 1ΒΌ lengths at Penn National June 3. It was just the fifth lifetime start for the son of Speightstown, and his third win. The three-year-old colt posted an equally impressive performance winning the Kent S. (G3) by 6-lengths July 15 at Delaware Park.

The Keeneland September Yearling Sale alumnus broke his maiden at first asking last summer at Saratoga for owner/breeder Green Lantern Stables and trainer Christophe Clement. He then ran fourth in the Pilgrim (G3) behind Oscar Performance, who went on to capture the Breeders' Cup Juvenile Turf (G1).

Frostmourne closed out his freshman season with a win the Awad Stakes at Belmont in late October. The stable worked on teaching the headstrong colt to relax over the winter, and he was a close second in the Woodburn Stakes at Aqueduct prior to his Penn Mile Stakes score.

A Kentucky-bred, Frostmourne is a half-brother to Karelian, winner of the 2010 Maker's Mark Mile (G1) at Keeneland. Their dam, the Theatrical (IRE) mare Leaning Tower, is a half-sister to Canadian champion Basqueian. Paramount Sales offered the colt during Book 1 of the 2015 Keeneland September Yearling Sale.