 Complete the following phrase:  Reus spent his youth career at Borussia Dortmund, prior to leaving for Rot Weiss Ahlen. He joined Borussia Mönchengladbach in 2009, and had his most successful season in 2012, scoring 18 goals and providing 12 assists in the Bundesliga to help Borussia Mönchengladbach secure a place in the following seasons UEFA Champions League. Reus returned to his hometown club Borussia Dortmund at the end of that season, helping the club reach the 