Stamkos scored his second power-play goal to push the lead to 3-1 at 14:47 when his centering pass went off of Ilya Lyubushkin’s stick and past Dostal. Stamkos had scored one goal in his previous 11 games.
His 204th power-play goal tied Wayne Gretzky for 17th in NHL history.
"That's kind of weird," Stamkos said. "It goes to show he did a lot of damage not on the power play too."
Anaheim had consecutive power plays early in the third period but failed to get a shot on goal with the man-advantage.
"When we did establish pressure, we didn't generate anything," Cronin said. "I don't know that we got a shot on the last two power plays. We kept saying on the bench to just get the puck down there, wrist it down there if you have to, and we couldn't even do that."
Calvin de Haan made it 4-1 at 9:06 of the third period with a wrist shot from the deep corner that beat Dostal to the near post. Lightning defensemen have accounted for eight goals in the past seven games.
"I think we were a little snakebit the first 40 games of the year," de Haan said. "It's been something we've been working on and something we've been preaching is putting pucks on the net from the blue line."
Brandon Hagel scored from the slot at 18:05 for the 5-1 final.
NOTES: Ducks forward Alex Killorn made his return here after playing his first 11 seasons with the Lightning. Killorn, who won the Stanley Cup with Tampa Bay in 2020 and 2021, was honored with a two-minute tribute video midway through the first period and received a loud ovation. "Just walking in the building, so many years, a lot of memories," Killorn said. "I was pushing all the emotions, and I'm pretty good at doing that, but once I saw the video it was really tough to hold it in. I feel so fortunate for everything I did here and the fans ... that ovation meant so much to me." ... Kucherov had his 20th three-point period of his NHL career. ... Ducks forward Brett Leason left the game early in the second period after taking a check from Lightning defenseman Emil Lilleberg.