Regrading the iron curtain descends event, while I love the wall events, I feel the discounts should be increased to atleast 75%. I'm at a mix of lvl 8 & lvl 9 walls. Upgrading all walls (135 nos) from lvl 9 to 10 costs 40mil. That increases exponentially after that. Even a 50% discount only brings the value to 20 mil which is still too high. 75% brings this down to 10mil, which is high enough to ensure its not used indiscriminately but low enough to actually give you some semblance of a benefit.