Plasmacannon: end game capabilities? All you need is tech (bulb) up to Philosophy. That's one my main problems with the Illians, they have tons of cool end game options which will never come into play if you raid the map with your three priests of winter, backed up by warriors, horses, adepts etc, which is all fairly early game stuff. Your traits aren't economically strong, but if you can back you conquest with some early cottages (and later Aristofarms, if you ever get there) defender & CHA are probably the best warring combo in this game as long as you use horses too.
Hint: only build Temples of the Hand in places where you actually want the terrain to become ice (tundra, desert, jungle tiles). These buildings are meant to grant the Illians very early terramorphing capabilities to utilize any land, they come even sooner than KotE (for a potential Scorch or Spring) and a LOT sooner than Vitalize which makes them really powerful. But you still don't want to shoot yourself in the foot and build them on a nice patch of FPs. They only grant +2
and don't return riverside commerce.
As an added bonus your neighbours are going to curse you for that
they don't really have any other early options but to scorch ice tiles and grow a forest on them and even that requires more technologies.
Illians are one of the earliest rushers in the game and their WS will guarantee that your first victim would sit there helpless while you get his land. If you go for a more traditional empire building game you will likely fall behind due to your lack of economic traits (in these cases building Samhain and casting Stasis when it completes might still help).