Yeah, a basic thing you can do to plan for a Dominions game is to see what is going to be the main magic for your nations. For example, MA Uruk most powerful mages are S2 and S3. The Astral 3 one has a random path, 25% of being S, so my most powerful mage (one in four) will be S4. Now, with item boosters that I can forge with Astral magic, he can be S5. There is another booster item but it’s S2E2, I will need first an Earth booster item to reach E2 in a Astral mage. Earth boots are E2 which I don’t have, in the end I empowered a E1 mage into E2, he can do now Earth boots and give them to a Astral mage, now he can do the S2E2 booster, so now my most powerful mage is S6. There are still more boosters to consider but they are higher level, for the end game, so for now I consider S6 as my real high end base magic (actually the ring of sorcery is S6 now to forge, so I can reach that, and end as a S7 mage).
Now I know that, I go to the inspector to see what is the most powerful rituals I can cast with S6, and some W2/N2/E2 magic, which is what I can get with water/nature/earth boosters.
In battle Astral is easier to boost, as there are not one but two spells to use as temporary boosters (Light of the Norther Star, Power of the Spheres), so your S6 would turn into S8, and you can boost it even more with Communions. So I can cast That’s Doom, Will of the Fates, Arcane Domination, Solar Brilliance, Unraveling and other high level Astral magic. In fact, with communions I can cast Master Enslave, which is a game winning spell, if I equip a pair of Penetration items.
Another thing to look is what crosspath spells you have in your nation, as they usually are more powerful than the average one-path spells. For example Magma Bolts (E1F1) is a bit more powerful than other damage level 1 spells, and spells like Bane Fire (D3F1) or Magma Eruption (E3F1) are excellent.
