[Alneyan]

On another note, the human Pretenders are best avoided, unless you are planning on getting a rainbow Pretender. More specifically, you should pick at least four paths (the figure is pretty much random) to warrant the use of a human Pretender; otherwise, you should have a look at more formidable Pretenders, like a Cyclops for Earth, or a Prince of Death for... you guess it. Even if you do want the rainbow Pretender, you might give at look at more sturdy Pretenders, since dying makes you lose one level in all your magic paths.

The reason is, human Pretenders (all the Pretenders with only Dominion 1, and regular stats) are very weak indeed, and can be taken down by weak rituals. If you are unlucky, a single Seeking Arrow could even kill your Great Sage. The asset of human Pretenders is their cheapness, especially to get new paths, but raising paths to high levels is very expensive with them: if the Cyclops has 3 Earth, it will only cost you 8 points to get a Cyclops to Earth 4, while it will cost a Great Sage 82(10+16+24+32) points to get him to that level. If you want further increases in Earth magic, it will only be worse, especially as the Cyclops has a higher base Dominion value.

Still on the topic of magic, what will be your need of magic? If you are fine with using low-level spells, 4 should be enough, but if you want to research the high-end stuff, an increase in your magic paths may be considered. For Earth, level 5 will give you nearly all spells, and while it is possible to go from level 4 to level 5, it requires having a foot slot on your Pretender (mounted Pretenders, Dragons and their ilk do not have such a slot). The other solution is to forge more expensive artifacts, like a Staff of Elemental Mastery (+1 to all four elements), or a Ring of Wizardry (+1 to all magic paths), but those are harder to get. The last way is starting up a blood economy, as there is one blood artifact that gives a +1 bonus to earth. Lastly, Earth has two battle rituals requiring more than level 5, "Army of Gold" and "Army of Lead". If you are aiming for those, you should get at least level 6 in Earth magic, and more if possible: Army of Lead requires level 7, and will knock your Pretender inconscious for the remainder of the battle. Those two battle enchantments mainly give a bonus to protection (total protection perhaps, or natural protection), as their other effect can be obtained much more easily.

As for Death, the same question rises: what level are the spells you wish to cast? 4 will be fine to cast virtually everything if you can snatch the +3 death artifact however, but there will only be one such artifact in the game. Still, even without it, it shouldn't be too expensive to research level 7 in Death magic, with two path boosters and a Ring of Sorcery (+1 to all sorcery paths).

Your Priestesses should be able to get relatively high in Nature magic without any help from your Pretender, thanks to the Ring of Sorcery: if you have a forge hammer, it will only cost 30 astral pearls, *fairly* cheap. With it, a Priestess reaches level 2 in Nature, allowing her to forge another item to get to level 3. If you have an Astrologer with a Nature random, you can give him all those items, and he can forge another item to reach level 4. If you really need more Nature magic, the Ring of Wizardry will allow you to get a single mage to level 5 in Nature, but I do not think there is much of interest at that level. Nature 4 will allow you to summon Lamia Queens, powerful mages in Sorcery paths, and a great complement to your own native mages (more focused on elemental magic, with astral everywhere).

Lastly, the Watchtower is good, if you intend to build several castles in the game: it may take you three towers to recruit as many troops as two castles, but they will cost exactly the same, and three towers allow you to recruit three commanders a turn (mages included), while only two castles limit your recruitment of commanders. That, and fortified provinces are much harder to take down, and will protect your magic sites from enemy raiders.