Assombalonga has been sidelined since February when he suffered a serious knee injury just weeks into Freedman's reign.
He was Forest's top goalscorer at the time, and the club have found it difficult to replace him given the fact they were under a transfer embargo in the summer.
Last night they drew 0-0 against Blackburn with lone striker Dexter Blackstock failing to register a single shot.
Freedman believes Forest, who are now unbeaten in four games, can still move towards the play-offs, and believes Assombalong and Matty Fryatt will be key to them doing so.
He said: "If you’re going to get promotion you need to string together six or seven wins on the bounce. We haven’t quite got that yet.
"We’re looking forward to more firepower coming back in January - Britt and Matty Fryatt.
"But as long as we can pick up points on the road and capitalise at home we’ll be in a position to mount a challenge."
Forest's season so far has not suggested play-offs, but Assombalonga is a real game changer, and last night was a game in which he could have made a real difference.
The team is improving defensively and are looking too good to be sucked into a relegation dogfight, so there is much to look forward to in 2016 if the club can get their star striker back and also get the transfer embargo removed.