So the province where I could recruit druids had become very important. It was even more when I found there the Ultimate Gate (turn 57), a site reducing all Conjuration spells by … 40% !!!

Later, it was very useful to get 18N Ivy Kings, 17D Mound fiends, 18F Flame spirits, 24N Fairy Queens (very important as they had crosspaths to some important national spells, and opened me to A4 and fog warriors), 54S Ether Gate, and more (Sea king for 33W, wraith lord for 24D, Fairy god mothers for 2D instead of 3D, Dark knowledge for 2D, etc…). I could have also taken elemental royalties for 30 gems but it looks like all were already taken…

In the very late game, I also stopped summoning knights in shining armor and started to spam my national dragon raiders for only 15N (instead of 25N).