Who are the men who will make their mark in Pool 6? ercrugby.com takes a look
Leo Cullen and Shane Jennings could come face to face with their old Leicester Tigers Team-mates when Pool 6 kicks-off with Leinster hosting the double champions in Dublin.
The two Irish international forwards were at the heart of the Tigers pack that reached the Heineken Cup final last season, but have opted to return home after two years with the English giants.
The Tigers have recruited All Blacks midfield general Aaron Mauger to plug the gap created by the departure of Daryl Gibson and have brought hooker Benjamin Kayser to Welford Road from Stade Français Paris. Wales Grand Slam hooker Mefin Davies has also switched to Leicester from Gloucester.
Toulouse have boosted their squad with the capture of robust New Zealand scrum half Byron Kelleher and have also taken South African-born No 8 Shaun Sowerby from Stade Français Paris and recruited Argentinean hooker Alberto Basualso from South America.
The triple champions kick-off their campaign against Edinburgh, the only Scottish team to have qualified for the knock-out stages when they reached the 2004 quarter-finals.
Edinburgh newcomers include Augusto Allori, an Argentine international front row forward, Ireland A lock Ben Gissing, Auckland Blues scrum half Ben Meyer and Scotland flanker Roland Reid.