I dont think giving them 2 pearls per turns a good idea, they are already fairly strong as-is. My basic plan was taking an imprisoned S9 Dom10 crystal soul with good scales. I prophetised my starting commander and recruited as many soulguard first turn as possible. Then i continue to ferry soulguard up to the frontline while recruiting many crystal souls who research evo6, thaum5 and then construction 8(then whatever i feel is needed). The soulguards(along with some shapers and mages i recruit if i run into tough opposition from another nation) are all i need to expand as they are very survivable(good defence, 100% regen and twist fate. With the bless they have 18mr which is great vrs illithids
) and tend to kill 1 unit each per turn (the sword brings them up to 16 attack with 20ap damage) so not much can stand against them. By the time i reach const7 i will usually have 15-20 crystal souls(that is if i have needed to recruit quite a few shapers and mages at my capitol) and have a huge astral gem stockpile at which point i will mass produce and equip golems.
Even before golems i have a powerful battle-tactic. I attack the enemy army with a scout to see if there are any astral mages, if there arent then thats fine and if there are i send squads of rangers to try and remove them. Once the enemy army has no astral mages my crystal souls are free to mind hunt all the commanders in it, generally making it rout as soon as its attacked.