I am over turn 400 in a standard time game, huge map. I intend to let it finish on time, just to make sure the MAF problem is gone. By the way, no CTDs either
A few more observations. The creepers should at least retain their current lifetime in each stage, and perhaps increase the blossom and rooting faces.
Since only young creepers are now invisible, there is no need to make it so invisibility can be lifted.
The creeper cycle introduced a fine strategic element for when it is best to use, and make it make sense to keep a number of creepers in strategic positions.
My conclusion so far is that the AI counts creepers as military units, meaning that it calculates your military strength including them, before deciding if you are too strong to attack. This IMO, should be changed. I only had a handful of Ghostwalkers and approx 20 creepers, and noone declared war on me, instead they were asking from my "mighty" empire to assist them in their wars.
I had written for the lack of incentives down the Arcane line, I just had forgotten about Necropolis and Flesh studio. However, in none of my 3 games with the Scions so far I could build the flesh studio, since there was no body mana and no mana nodes in the vicinity of my empire.
The spawn rate for creepers appears to be just fine for me. I used them to have constant spies all over the continent and, when I accepted to help someone, they did a nice job in poisoning the enemy, although all of them lost. I managed to create a couple haunted lands, though, with 2 retreating young creepers

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BtW, it appears that the blossomed(If I am not mistaken) creeper's ability is very easy to resist. I don't think I saw a percentage written in the description, can you enlighten me on the subject?