Lausanne - Leinster will have to negotiate a tough pool including French Top 14 outfit Toulouse and strong English duo Bath and Wasps in a bid to defend their European Champions Cup in October.
The four clubs have a total of 11 European titles between them, Leinster winning in 2017, 2012, 2011 and 2009, the Irish province's most recent victory pulling them level with Toulouse, winners in 1996, 2003, 2005 and 2010. Bath claimed the Cup in 1998, while Wasps won twice, in 2004 and 2007.
In the draw made in Lausanne on Wednesday, English giants Saracens were given a more sympathetic draw, in Pool 3 with Glasgow, Cardiff and Lyon.
Pool 2 sees French Top 14 champions Castres take on Munster, Exeter and Gloucester, while Scarlets top a testing Pool 4 also comprising last season's runners-up Racing 92, two-time champions Leicester and 1999 victors Ulster.
Newcastle's baptism of fire in Pool 5 will include complicated trips away to French heavyweights Montpellier and three-time winners Toulon, and slightly closer to home, across the border to Edinburgh.
Draws for the European Champions and Challenge Cups on Wednesday:
European Champions Cup
Pool 1: Leinster (IRL), Wasps (ENG), Toulouse (FRA), Bath (ENG)
Pool 2: Castres (FRA), Exeter (ENG), Munster (IRL), Gloucester (ENG)
Pool 3: Saracens (ENG), Glasgow (SCO), Lyon (FRA), Cardiff (WAL)
Pool 4: Scarlets (WAL), Racing 92 (FRA), Leicester (ENG), Ulster (IRL)
Pool 5: Montpellier (FRA), Newcastle (ENG), Edinburgh (SCO), Toulon (FRA)
European Challenge Cup
Pool 1: Northampton (ENG), Clermont (FRA), Dragons (WAL), Timisoara (ROM)
Pool 2: Pau (FRA), Ospreys (WAL), Worcester (ENG), Stade Francais (FRA)
Pool 3: Sale (ENG), Connacht (IRL), Bordeaux-Begles (FRA), Perpignan (FRA)
Pool 4: La Rochelle (FRA), Zebre (ITA), Bristol (ENG), Enisei-STM (RUS)
Pool 5: Benetton (ITA), Harlequins (ENG), Agen (FRA), Grenoble (FRA)
Note: Five pool winners plus three best runners-up qualify for knock-out phase
Round 1: October 12/13/14
Round 2: October 19/20/21
Round 3: December 7/8/9
Round 4: December 14/15/16
Round 5: January 11/12/13
Round 6: January 18/19/20
Quarter-finals: March 29/30/31
Semi-finals: April 19/20/21
At St James' Park, Newcastle, England
Finals: Challenge Cup final, May 10; Champions Cup final, May 11