Neuchatel - French and European champions Toulon have been handed a tough draw in the inaugural European Rugby Champions Cup made in Neuchatel on Tuesday.
The European Champions Cup will replace the European Cup from the 2014/2015 season.
And two-time European champions Toulon will face English club Leicester, also double winners, Irish province Ulster and Welsh side Llanelli Scarlets in Pool Three.
"Usually there's only one group of death, but they all look tough pools," said Leinster and Ireland hooker Sean Cronin whose team are in Pool Two with Harlequins, Castres and Wasps.
"Leinster have a proud tradition in Europe and it will be a huge focus for us next season," he added of the 2009, 2011 and 2012 winners.
"We want to prove ourselves again in Europe next season, even though it will be strange not to have Leo (Cullen) and Brian (O'Driscoll) on the pitch."
Scarlets head coach Simon Easterby admitted their pool looked the toughest.
"Having the back-to-back European champions is a huge challenge and going to the south of France means you are going to play in a real cauldron," said Easterby.
"Toulon have a fantastic group of players, genuine world stars, but we showed away to Racing Metro 92 last season that we could get a result in France."
The three other semi-finalists in 2014, including French club Clermont, are in another tough Pool One, which includes Saracens, Irish province Munster and England's Sale Sharks.
"We have picked up three of the best teams in Europe in our pool," said Munster head coach Anthony Foley.
"Looking at the rest of the tournament I think this is an even stronger draw than in previous years.
"All the games in our pool will be big games."
Saracens, European and Premiership runners-up, will be desperately trying to nail down a title next season.
English champions Northampton, who beat Saracens in last month's Premiership final, have been drawn in Pool Five alongside France's Racing Metro, Welsh side Ospreys and Italians Treviso.
Four-time winners Toulouse will contest Pool Four with Glasgow, Montpellier and Bath.
"It is a fantastic pool to be involved in and we will be up against great teams and playing them in great places," said Glasgow head coach Gregor Townsend, who is relishing clashing with former club Montpellier.
"They are one of the best teams in France and they are a great attacking side who score plenty of points," he said.
"Toulouse failed to reach the French semi-finals for the first time in ages but remain a quality side with a huge pool of players to call on.
"Bath are a rapidly improving team."
The European Rugby Champions Cup will be one of three cross-border competitions and will be joined by the Challenge Cup and a new competition called the qualifying competition.
European Champions Cup
Pool 1: Saracens (ENG), Munster (IRL), Clermont (FRA), Sale Sharks (ENG)
Pool 2: Leinster (IRL), Castres (FRA), Harlequins (ENG), Wasps (ENG)
Pool 3: Toulon (FRA), Leicester Tigers (ENG), Ulster (IRL), Scarlets (WAL)
Pool 4: Glasgow (SCO), Montpellier (FRA), Bath (ENG), Toulouse (FRA)
Pool 5: Northampton Saints (ENG), Racing Metro (FRA), Ospreys (WAL), Treviso (ITA)
European Challenge Cup
Pool 1: Cardiff (WAL), London Irish (ENG), Grenoble (FRA), 1st qualifier FIRA play-off
Pool 2: Exeter (ENG), Bayonne (FRA), Connacht (IRL), La Rochelle (FRA)
Pool 3: Stade Francais (FRA), Newport (WAL), Newcastle (ENG), 2nd qualifier FIRA play-off
Pool 4: Edinburgh (SCO), Bordeaux-Begles (FRA), London Welsh (ENG), Lyon (FRA)
Pool 5: Gloucester (ENG), Brive (FRA), Zebre (ITA), Oyonnax (FRA)