I suppose sharing the details about the communion I used harms nobody, so here it goes(a slightly improved version):
Slaves x14 (all S1 mages): Communion Slave, Twist Fate, Stellar Cascades x3, Spells
Master #1 (S1E1): Communion Master, Summon Earthpower, Personal Luck, Gifts From the Heavens x2, Spells
Master #2 (S1): Communion Master, Light of the North Star, Enslave Mind x3, Spells
Master #3 (S2B1): Communion Master, Power of the Spheres, Reinvigoration, Life for a Life(if expecting to fight SC), Reinvigoration, Spells
Sit back and enjoy the show.
Remember to add in a bit of chaff to slow down the enemy for a turn or two so you get the communion online. I had my pretender there to play the slow down part because I was really short on troops.
There you have it in its full glory.
The really nice thing in this particular communion was that I got some real firepower out of those otherwise useless S1 mages who normally just sit in the lab doing research.