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A "long game" strategy needs to have a big payoff in the late game in order to make the early sacrifices worth it. I'm not sure what you get by taking low dominion and dormant with AE Ermor, which has more points from scales than any other nation. Taking drain just causes problems by making your research bad, so in the one part of the game where you should be dominant (the end) you're not. And, taking low dominion just makes your immortality worse. On top of it all, human players will hate you just for being AE Ermor, so your chances of getting through to the late game unmolested are quite small.

AE Ermor has enough points to take an awake pretender, decent magic paths, and luck+magic, or a dormant pretender and really good magic with the same scales, and do it all with decent dominion. Since AE can't use blood and the liches all start with a bunch of death, you can afford to just buy all the paths you want. For a more rainbow, less combat-oriented lich you can take the master lich instead of the lich queen.

If you sacrifice magic and awake you can buy an extra level or two in most of your paths, but that's not that important - by the time there are spells that you can actually cast with those levels, you'll have enough gems to forge booster items or just empower if you must.

With a rainbow mage pretender, your biggest constraint is not paths, or even gems, but simply not having enough time for all the stuff you will need to do.