Dai Young’s men channelled the emotion of the afternoon into a rapid start, with scores from Jake Cooper-Woolley, Nathan Hughes, Tom Varndell and Ben Jacobs wrapping up a bonus point before half time.
Guy Thompson joined them across the whitewash in the second half while Varndell and Jacobs – with the last action of the game – completed their doubles.
The Wasps adventure will now continue at the Ricoh Arena with the return of Aviva Premiership Rugby next weekend
and for Haskell, the club’s spirit will burn just as bright in Coventry.
“This club has had a great legacy in the European Cup and there have been so many good memories here,” said Haskell, whose side are one point behind Pool 2 leaders Harlequins and Leinster.
“To finish against a European team, one of our old rivals in Cas, is great. For a lot of the boys it’s difficult to explain the emotion because I’ve supported Wasps as a kid, coming here was my first home ground.
“It’s hard to say goodbye but lot of the fans will come with us which is positive, some won’t be able to make it, and it is important we respect them and thank them for all the time they’ve given us.
“It’s always been about the fans, the people – that’s what Wasps have always been about.”
On Saturday, Harlequins came within a whisker of a famous fightback in Dublin after falling to Leinster 14-13.
Quins had won the first of the double header at the Stoop last week but leading by 11-0 at half time, Leinster seemed on course for victory.
Man-of-the-match Ian Madigan had kicked two penalties while scrum-half Isaac Boss had surged over in the corner – but Conor O'Shea's men made their scrum count in the second half.
That push saw England full-back Mike Brown plunder a converted try while Tim Swiel, at fly-half in place of the injured Nick Evans, nailed two penalties. However, a 71st minute penalty from Madigan proved the decisive factor.
And O’Shea couldn’t hide his frustration after the game before admitting patience so nearly paid off.
“We are a very frustrated group of players and coaches because we came close to getting what would have been a historic victory,” he said.
“The message at half time was to be patient because, although we didn’t get on the scoreboard in the first half, we felt there was room there.
“I felt that on the balance of play in the second half we probably deserved the win but I am sure they will be thinking the same thing.”
At Franklin’s Gardens Northampton Saints fired a warning shot to the rest of Europe after an 11-try showing over Benetton Treviso.
Ken Pisi and Samu Manoa both scored hat-tricks to help the Aviva Premiership Rugby leaders secure a club European record 67-0 triumph to stay on course to reach the quarter-finals.
The hosts exerted their dominance early on as their scrum forced a penalty try before George North, Kahn Fotuali'I, George Pisi and Ben Foden joined the hat-trick heroes on the scoresheet.
Mallinder said: "We hoped for but didn't expect that win. We had to work hard for our bonus point last week, but it always helps coming back home.
"It was important that we made a good start and kept it clinical and professional. Once we got ahead, their heads certainly dropped.
"We didn't get too carried away, we didn't play sevens rugby, we kept our shape and discipline. It was a good professional performance."
Saracens bested Sale Sharks by 28-15 in an all-Aviva Premiership Rugby clash at Allianz Park – yet Mark McCall concedes his side could live to rue the lack of a bonus point.
The hosts took a 6-0 lead through two Owen Farrell penalties before Sale hit back as Nathan Hines touched down only for Alex Goode to cross over on 36 minutes.
Nick MacLeod's penalty on the stroke of half time made it 11-8 but Mark McCall's side took control through tries from substitute Ben Ransom and Billy Vunipola before Eifion Lewis Roberts's late consolation score.
But McCall said: “We might live to regret not getting the bonus point, but what you want is to be in control going into rounds five and six.
"We have Munster coming here and it's going to be a titanic match.
"But to have 13 points at this stage is OK and if we win both games we win the group. At least it's in our hands.”
Leicester Tigers could not keep pace with European champions Toulon in a 23-8 loss, despite Blaine Scully’s try giving them brief hope before the break.
Former All Black lock Ali Williams crashed over on 11 minutes, with Wales star Leigh Halfpenny landing three penalties before the visitors responded through Scully to trail 16-5 at the interval.
Mathieu Bastareaud's converted try then secured the French side revenge for last weekend's defeat as Owen Williams toiled for the Tigers to put their European hopes in doubt.
And on Friday, Sam Burgess made his first start for Bath Rugby as the Rec outfit brushed aside Montpellier in a 32-12 bonus-point victory.
Burgess, lined up in the centres, was heavily involved in the build up to Matt Banahan's first two tries.
But Banahan stole the limelight by notching a hat-trick of scores, while Horacio Agulla went over for the all-important fourth try late on – handing Bath a lifeline six points behind leaders Toulouse in Pool 4.
Wasps 44 Castres 17
Tries: Cooper-Woolley, Hughes, Varndell 2, Jacobs 2, Thompson
Conversions: Goode, Lozowski
Tries: Rallier, Evans, Houerie
Northampton Saints 67 Benetton Treviso 0
Tries: Penalty, North, Fotuali'i, K Pisi 3, G Pisi, Manoa 3, Foden
Conversions: Myler 4 Wilson 2
Leinster 14 Harlequins 13
Penalties: Madigan 3
Penalties: Swiel 2
Toulon 23 Leicester Tigers 8
Tries: Williams, Bastareaud
Penalties: Halfpenny 3
Saracens 28 Sale Sharks 15
Tries: Goode, Ransom, Vunipola
Conversions: Farrell 2
Penalties: Farrell 3
Tries: Hines, Lewis-Roberts
Bath Rugby 32 Montpellier 12
Tries: Banahan 3, Agulla
Cons: Ford 3
Pens: Ford 2
Tries: Tulou, Ivaldi
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