The Montreal Impact haven't been in the CONCACAF Champions League since their magical run all the way to the finals back in 2015. Since then they haven't made it back once and for them to get back in it in 2018 it will be even harder.
With CONCACAF mixing up the rules for qualifications with Canadian teams, this year will be a long and tougher path to qualify for the 2018 CONCACAF Champions League. Toronto FC the winner of the 2016 Voyageurs Cup was supposed to become Canada's sole entry into the Group Stage of the 2017–18 CONCACAF Champions League. However, due to that tournament's restructuring, it was later announced that the Canadian representative at the 2018 CONCACAF Champions League will be the determined by a playoff match between Toronto FC and the 2017 Canadian Championship winner.
Essentially, the Montreal Impact wouldn't qualify for the 2018 CONCACAF Champions League if they beat Toronto in this year's Voyageurs Cup. If they do in fact beat Toronto FC in the two-legged final there would then be a playoff matchup to be hosted by Toronto FC on August 9 to decide which Canadian team qualifies for the 2018 CONCACAF Champions League.
Here's a Montreal Impact Canadain Championship cheat sheet to the 2018 CONCACAF Champions League and so on. Posted by the Montreal Impact on their Twitter page.