[Edratman]

You initially asked for a powerful early nation. I would suggest Helheim, with good troops and glamour which will give good kill ratios. You will need independent archers, but that is easy. Helheim will allow you to expand early and easily.

Another easy nation is Nefelheim with good sacred giants. Go for good scales, and at least a 4 nature/4 earth bless using a dormant rainbow pretender for searching. On your setup screen go for 300 gold, 300 resources and 300 supply. On normal difficulty you should be able to crush the AI on a small map (40-50 prov) with 3 opponents just with the sacred giants. Game will seem easy.

After a couple of games with the "HEIMS" to get a feel for the game, go to a circa 250 province map with 15 opponents still staying with whichever Heim you liked best. Stay at the 300 settings of gold/resource/supply. There are some good maps that come with the game in that size range. You should be able to expand like mad early. Here it is very likely you will see the limitations of the Heims and encounter the complexities of the game because the AI overwhelm you unless you are a better player than I .

Then you are on your own for the wonderful experience that is DOM3.