FedSlayer, don't forget buffs like mistform or ironskin/invunerability on your communion slaves if you can take the time - personal luck is good too, anything to keep 'em safe. Quickness is also great if you can combine it with a banner of the damned if you have a limited number of slaves(2 drain life casts per slave per turn should handle fatigue) and ranged weapons+quickness is also nice.
For astral mages, a pretender with high magic showing up, perhaps via teleportation, can take out a large number of enemy mages who want to magic duel you. Rishis can get S4 iirc, so you will probably need either very high astral - I think 7-8 gives you 100% chance to beat S4 but I'm not sure - or immortality would be best to keep your god safe.
The threat of a teleporting god should keep enemy magic dueling low, although raiding parties/other small forces should probably avoid using many astral mages.
Master alchemists, perhaps taking advantage of crystal/slave matrixes(slaves on regular alchemists might be best for path synergy), could pick up the slack when you don't have god-support for your forces.
And as for making items to boost your astral power for protection, I don't think item/spell/communion boosts actually help against magic duel, and even if they do the enemy has natural S4+items to use against you.
A communion consisting of many slaves - perhaps thugs(who can have flying shoes instead of mass flight) with slave matrixes buffed with phoenix pyre, mass flight and some other buffs such as summon earthpower, invunerability, quickness, mistform, mirror image ect may seem a little silly but can be devastating. With either summon earthpower and reinvigoratino items(and possibly relief), or simply expendable slaves, you can do alot of damage to an enemy while the flight allows them to reach the enemy quickly to avoid your own troops. If the thugs trample it is even better as they can reach the middle of the enemy formation.
Just tossing out some random ideas while bored and sleep deprived - I hope you enjoyed reading
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