1: Catacomb Libralus gives +30xp to new adept units, and is pretty early in the tech tree. The optimal strategy for me became just creating adepts, casting wane a bunch, then deleting the xp-drained adepts and building new ones. Throw in a warriors district, a command post, and some other stuff, and you can pump out an adept with 70 or more xp every turn.
2: Having wane remove xp is not very fun. I'd recommend just making it so that each cast of wane makes the next cast slightly more difficult to cast. So for example maybe the first cast requires 100xp total, and then 125 or so xp, then 150, and so on.
3: You start with so much xp that training isn't very useful or powerful. It was so weak, and I was casting wane so often, that it just didn't matter.
2: Having wane remove xp is not very fun. I'd recommend just making it so that each cast of wane makes the next cast slightly more difficult to cast. So for example maybe the first cast requires 100xp total, and then 125 or so xp, then 150, and so on.
3: You start with so much xp that training isn't very useful or powerful. It was so weak, and I was casting wane so often, that it just didn't matter.