 Complete the following phrase:  The competition consisted of the four Welsh Pro12 teams and the twelve English Premiership clubs arranged in pools of three English and one Welsh team. English clubs were allocated to the pools depending on their final positions in the 201516 Aviva Premiership. Teams played two home and two away pool matches, with teams in Pools 1 and 4 playing each other and teams in Pools 2 and 3 playing each other. The top team from each pool qualified for the semi-finals. The competition took place during the Autumn International window and during the 