Talk about frustrating....
I just had my THIRD Blight event in my game.
Number 1 came fairly early in the Epic speed game due to a lot of wars, mostly instigated by the Sheaim.
I was able to drive the AC down to the low 20s mostly by sanctifying ruins where it stayed for a good 100+ turns.
However, it crept up and Number 2 came when it hit 30 again.
I went through all Four Horsemen. I summoned Basium through the Gate and the AC was at 76.
Number 3 immediately came.
I am certain these are all Blight, and I will be shutting off the Counter my next game waiting for a fix on this.