Leinster ran in nine tries as they outclassed Northampton to win 60-13 at the Aviva Stadium, moving six points clear in Pool 4 of the Champions Cup.
Adam Byrne opened the try scoring for Leinster, before Ken Pisi responded for Saints.
Luke McGrath and another from Byrne snatched the advantage back for the hosts before the break, with Sean O'Brien going over right on half-time for a 29-13 lead.
Tadhg Furlong and Sean Cronin crossed within the first six minutes of the second-half, Isa Nacewa claiming the seventh soon after, before Rory O'Loughlin and Nacewa finished the scoring.
The Pool 4 meeting between the two sides saw Northampton looking to make amends for their 37-10 defeat in the return fixture last week. They had to win to stand any chance of qualifying into the knockout rounds, but didn't start well.
Falling behind only five minutes in, Leinster took the lead with Adam Byrne's first try in Europe. Devin Toner charged down a clearance, with the pressure telling and seeing Byrne over. Nacewa narrowly missed the conversion, in a first half that was filled with excitement.
Stephen Myler struck a duo of penalties in quick succession to take the lead for Saints, before Pisi notched their first try. The TMO had to double check, but gave the all clear after Pisi stole possession under his posts to lead a counter all the way downfield. The conversion followed, but Leinster were right back into the game within minutes.
Nacewa added a penalty, before a pair of tries took the wind right out of Northampton. The first of the pair came from McGrath, sneaking through a gap in the Northampton backline, going in just by the posts.
Nacewa converted, with Byrne grabbing his second try almost immediately after the restart. Throwing bodies at the Leinster defence, the ball hit the deck and Byrne was able to steam forward unopposed for the third Leinster try.
And the game was almost killed off right in half-time. The hosts made it four tries in 40 minutes after having the advantage, O'Brien peeled away from the back of a drive and swivelled his way over. Nacewa added the two as Leinster went in 29-13 to the good.
The second 40 started as badly as the first finished for Saints, with two more tries turning it into a rout.
With the bonus point already secured, Leinster battered their way over the line after throwing bodies forward. Furlong was the man in control, Nacewa converting.
Try number six followed. Ross Byrne's pass opened up the space for Cronin, who did the work earlier in the build-up.
Things went from bad to worse as Jamie Gibson was shown a yellow, before Nacewa went through for the latest try, going over in the corner.
Still with the extra man, replacement O'Loughlin added to Saints woes as passes on the touchline sent him through unopposed, making it 55-13.
Nacewa got his second of the half, taking advantage of Pisi's misjudgement to nip in and cross the line as the tries continued to fall on the depleted Saints. That's where it ended for Northampton, as they fell to a 60-13 rout in Dublin.
Tries: A Byrne 2, L McGrath, O'Brien, Furlong, Cronin, Nacewa 2, O'Loughlin
Cons: Nacewa 4, R Byrne 2
Try: K Pisi
Pens: Myler 2
Yellow Card: Gibson (54 min)
Leinster: 15 Zane Kirchner, 14 Adam Byrne, 13 Garry Ringrose, 12 Robbie Henshaw, 11 Isa Nacewa (c), 10 Ross Byrne, 9 Luke McGrath, 8 Jamie Heaslip, 7 Josh van der Flier, 6 Sean O’Brien, 5 Hayden Triggs, 4 Devin Toner, 3 Tadhg Furlong, 2 Sean Cronin, 1 Jack McGrath
Replacements: 16 James Tracy, 17 Cian Healy, 18 Michael Bent, 19 Rhys Ruddock, 20 Jack Conan, 21 Jamison Gibson-Park, 22 Noel Reid, 23 Rory O’Loughlin
Northampton Saints: 15 Ahsee Tuala, 14 Ken Pisi, 13 George Pisi(c), 12 JJ Hanrahan, 11 Tom Collins, 10 Stephen Myler, 9 Nic Groom, 8 Teimana Harrison, 7 Calum Clark, 6 Jamie Gibson, 5 James Craig, 4 Api Ratuniyarawa, 3 Kieran Brookes, 2 Charlie Clare, 1 Ethan Waller
Replacements: 16 James Fish, 17 Alex Waller, 18 Paul Hill, 19 Michael Paterson, 20 Ben Nutley, 21 Tom Kessell, 22 Rory Hutchinson, 23 James Wilson
Referee: Romain Poite (France)
Assistant Referees: Tual Trainini (France), Mathieu Noirot (France)
TMO: Eric Briquet-Campin (France)