The Polish side led 1-0 from their home leg and extended their advantage to 2-0 and 4-1 as tonight's return match unfolded.
Their Belgian opponents hit back through Oscar Duarte and an injury-time strike from Tom de Sutter but had left themselves too much to do.
Turkish side Bursaspor, who played in the Champions League three seasons ago, were dumped out after a 3-0 second-leg loss to Vojvodina.
The Crocs looked in good shape after drawing 2-2 in Serbia last week but were sunk by goals from Abubakar Oumaru, Stojan Vranjes and Andrija Kaludjerovic.
Hajduk Split were beaten 1-0 for the second week running by Dila Gori, substitute Grigol Dolidze scoring three minutes after his introduction to see the Georgian side through.
Eredivisie side Vitesse Arnhem were another casualty after Gheorghe Grozav's goal five minutes into injury time earned Romanian side Petrolul Ploiesti a 3-2 aggregate win.
The remainder of the bigger names made it through, led by St Etienne after Brandao, Romain Hamouma and Banel Nicolita earned a second 3-0 win over Milsami.
Cesar Navas and Roman Eremenko earned Rubin Kazan a 2-0 win over Randers and a 4-1 aggregate success while Maccabi Haifa beat Ventspils 3-0 after a goalless first leg, Rayo scoring twice.
Sevilla crushed Mladost Podgorica 6-1 in Montenegro with two goals apiece for Raul Rusescu and Koke Andujar to complete a 9-1 aggregate win.
Udinese beat Siroki Brijeg 4-0 at home and 7-1 on aggregate while Standard Liege enjoyed a second successive 2-1 win over Xanthi.
Stuttgart settled for an away-goals success against Botev Plovdiv, with a goalless home leg this evening having drawn 1-1 in Bulgaria.
Pandurii beat Hapoel Tel Aviv 2-1 on the night and 3-2 on aggregate while Lithuania's Zalgiris upset Lech Poznan on away goals. They lost 2-1 in Poland after late goals from Poznan's Lukasz Teodorczyk and a Luka Peric own goal levelled the tie on aggregate at 2-2, but it was enough to go through.
Norwegians Tromso scraped past Differdange on penalties after the Luxembourg side won their second leg 1-0. Thomas Drage missed Tromso's first penalty but Mathias Janisch hit the post and Marcus Sahlman saved from Differdange captain Philippe Lebresne.
Czech side Slovan Liberec beat Zurich 2-1 for the second successive week, Trabzonspor held on to their 1-0 first-leg scoreline against Dinamo Minsk and Rapid Vienna beat Asteras Tripolis 3-1 on the night after a 1-1 first-leg draw.