Scott Hotham grabbed the winner in the Devils’ 3-2 win on home ice, while Joey Haddad, Chris Culligan and Gleason Fournier and Gleason Fournier were on target in their 3-1 road success.
Dundee Stars are through to their first-ever play-off finals weekend after a 6-1 overall win against Braehead Clan.
The Stars secured a 3-1 victory at home and followed up with an impressive 3-0 success in the reverse fixture – Justin Faryna, Joey Sides and Kevin Hart were on target in the second leg.
Derrick Walser (2) led the Way as the Giants triumphed 4-2 at home, while Blair Riley matched the feat in their 4-1 win in the return game.
The Steelers looked on course to go through when they held a 4-0 lead heading into the final stages of the second leg, but Chris Lawrence scored with eight seconds left to send the game to overtime.
Despite Lawrence’s dramatic goal, the momentum did not swing in the Panthers favour as Guillaume Desbiens scored the Steelers’ winner just over 90 seconds into the extra period.
The semi-finals see Cardiff face Dundee, while Belfast meet Sheffield.
(Image permission: Cardiff Devils)