I know it's a modded game but I don't know of any mods which enable the last building or the spell.   For the modders, are there?  You can check out my Mods folder content on my website at "legendaryheroesmods.stevenaus.fastmail.com.au" - the instructions are in Reply #31 at:

https://forums.elementalgame.com/456046/page/2

Any ideas guys?  I thought for the first game I might have forgotten to turn Spell of Making off, but I was sure I turned it off in the second game, and thinking about it, I was sure that I had turned it off in the first game too.

Also, the map didn't appear to show where the casting Sov was.  This is essential information for any game ending spell.

NOTE: I have DLC01-DLC04 (everything except the Leaders Pack) bought and enabled, a few custom .dxpack files, and no other core files that could be expected to ignore the Spell of Making being turned off and still being used by AI players.