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The Steelers won 6-5 in second overtime to deny the Devils a grand slam.
"What an epic game. I won't forget this one for a long time," Sarich told BBC Radio Sheffield after Levi Nelson' winning goal saw Sheffield come back from 3-1 down to clinch victory.
"We worked so hard for it. Hats off to Cardiff as well."
The Devils had been bidding to become the first team to win an Elite Ice Hockey League grand slam since 2012-13.
But they were denied by the Steelers, who also came from behind to beat Nottingham Panthers earlier in the play-offs.
"To pull the rabbit out of the hat against Nottingham and now to do it here in double overtime, it is a fairytale," Sarich added.
"This is right up there, it is tops. What a battle to get here and then, to do it like that, we're really happy."
The Steelers had not won the Elite League play-offs since 2013-14.
Sheffield Steelers defender Rodney Sarich says Sunday's dramatic overtime win over Cardiff Devils in the Elite League play-off was a "fairytale".