Nathan MacKinnon extended his point streak to 16 games with an assist, and Valeri Nichushkin and Jonathan Drouin each had two assists for the Avalanche (44-20-5), who have outscored their opponents 31-13 during the streak. Justus Annunen made 30 saves.
Nathan Walker had a goal and an assist for the Blues (36-30-3), who had their four-game winning streak end. Jordan Binnington made 31 saves.
Rantanen scored his second of the game to tie it 3-3 at 18:46 of the second period on the power play, redirecting a pass from Drouin in the slot past Binnington.
The forward completed his hat trick to make it 4-3 at 4:15 of the third period with a one-timer in the slot after Nichushkin forced a turnover in the offensive zone.
Rantanen put the Avalanche ahead 1-0 at 6:36 of the first period with a wrist shot in the slot off a centering pass from MacKinnon.
Walker tied it 1-1 at 8:48, taking a pass from Scott Perunovich as he came off the bench and beating Annunen with a wrist shot in the left circle.
Alexey Toropchenko made it 2-1 at 4:44 of the second period when he crashed the net and put in a rebound in front after Justin Faulk’s wrist shot.
Casey Mittelstadt tied it 2-2 at 6:41 with a snap shot in the slot off a pass from Samuel Girard below the goal line.
Brayden Schenn gave the Blues a 3-2 lead at 8:43 when he one-timed a pass from Jake Neighbours on a 2-on-1 rush.
