Holders Exeter will begin their Champions Cup defence with challenging group-stage matches against Toulouse and Glasgow when next season's new-look competition begins in December.
The new format - enforced by the pandemic and only for the 2020-21 season - features two pools of 12.
The four highest-ranked clubs in each pool will reach the quarter-finals.
The quarter-finals will be played over two legs and the clubs ranked fifth to eighth in each pool will drop into the knockout stage of the European Challenge Cup.
The opening round of games will take place 11-13 December.
Alongside Premiership winners Exeter in Pool B, Pro14 finalists Ulster face Gloucester and four-time winners Toulouse in their group games.
In Pool A, Pro14 champions Leinster will play Montpellier and Northampton, while Harlequins and Connacht have been drawn against last season's runners-up Racing 92.
Premiership runners-up Wasps play Dragons and Montpellier, while Munster face Quins and Clermont.
Clubs only play opponents in the same pool but cannot play other teams from the same domestic league.