Killorn missed Game 2 of the series against the Canadiens with a lower body injury, potentially the result of taking a puck to the skate in Game 1.
The Lightning won both games in Tampa and hold a 2-0 series lead over the Canadiens.
Forward Tyler Johnson moved up to the line with Steven Stamkos and Anthony Cirelli in Game 2 to take the place of Killorn. Johnson picked up the primary assist on Cirelli's second-period goal that gave Tampa Bay a 1-0 lead in the 3-1 victory.
"Killer's a bigger body than Johnny, [who is] more of a speedy player who can beat you off the rush. But in the end, the competitive spirit is the same," Lightning coach Jon Cooper said of the two players.
He said that since Cirelli and Killorn play together on the penalty kill, they've developed a chemistry that's not as easy to replicate with Johnson filling in at 5-on-5.
"But it's not like you're inserting guys that are rookies on the team," Cooper said. "It's guys that have played together for a long period of time. Maybe it takes a couple shift adjustments, but the guys know each other. It's a pretty seamless transition."
With Killorn out, the Lightning will have the same lineup in Game 3 as they had in the Game 2 win, with Mathieu Joseph in Johnson's old spot on a line with Ross Colton and Pat Maroon. Joseph played only 6 minutes and 23 seconds in Game 2.