Scarlets and Exeter dominate after they triumphed in the PRO12 and Premiership finals.
Ireland fly-half Ian Madigan and Scotland prop WP Nel are among the final additions to the Barbarians squad to face England and Ulster.
Players from Super Rugby rub shoulders with the PRO12, Premiership and Top 14, plus two sets of brothers make the cut.
With 11 Irish players away with the Lions, Joe Schmidt has handed eight uncapped players a chance to show what they can do.
Leinster were denied top spot after suffering their first PRO12 defeat since December with a 17-13 loss to Ulster.
Munster make up more than a third of the Guinness PRO12 team of the season with six of their players included.
Ospreys held off a second-half fightback from Ulster to win 24-10 and put themselves in a good position to reach the play-offs.
Canada's Sevens success, Saracens in Europe and the Barrett brothers feature in Will Greenwood's selections this week.
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