Apologizes if this has been asked before, but a quick search on the forums and in the FAQ did not yield an answer.  If Nurgle has the Leper upgrade card, which reduces the power point cost to summon a leper to 0 if Nurgle has no figures in the region, what is the cost of summoning a Leper into a region in which Tzeentch has played Temporal Stasis - assuming Nurgle has no other figures there, of course?

This question come up for the first time a few days ago and we all agreed the cost would be two.  However, the more I thought about it the more it bothered me.  The upgrade card does not specify that the "printed" cost is reduced to 0, just that the cost is 0 - so an argument could be made that even if other effects increase the cost of playing a figure, the upgrade card still reduces it to 0.  I could not find a rule that says upgrade cards take precedence over chaos cards, so I was hoping my fellow FFG and Warhammer fans could help me out.

I believe Temporal Stasis says "...to this region" so I would say yes, it will cost you 2+0 = 2 power points to summon that unit. The upgrade card only reduces your general summoning cost of a cultist.

While there is no explicit rule, it seems Chaos Cards come first when it relates to effect in regions.