It was more than a year ago that a group of 10 former N.H.L. players sued the league for, in essence, ignoring the growing evidence surrounding the long-term effects of concussions.

For the past 15 months, amid the quiet consolidation of subsequent suits and obscure legal wrangling, the case against the N.H.L. has been a faint echo of the similarly constructed class-action suit against the N.F.L. That case involved thousands of former players and was settled in 2013 for $765 million. (The cap was subsequently lifted to cover unlimited damages and still awaits judicial approval.)

Two events in recent weeks nudged hockey’s face-off over concussions back to center ice. First, 29 more former players joined the class-action suit, nearly doubling the number of named plaintiffs. Then Steve Montador, a 10-year N.H.L. veteran with a history of concussions, was found dead at 35 in his Ontario home Sunday.

“As more and more players learn about the claims and see the medical challenges their fellow alumni are experiencing, there is increased momentum in support of the litigation,” said Charles Zimmerman, co-lead counsel for the plaintiffs. “The N.H.L. can no longer ignore the impact of repeated head trauma and must finally acknowledge the serious conditions that retired players are facing.”