Board Thread:Questions and Answers/@comment-68.166.176.250-20150522164625/@comment-26123047-20150605120113

Sometimes tier 3 and tier 4 upgrades cost bloonstones, sometimes they don't. It seems that they often cost bloonstones in the evenings, and they often only cost city cash in the mornings. I haven't exhaustively tested that, though. For the people who think they cost bloonstones all the time, here's a screenshot from my game, taken at around 8AM local time:http://imgur.com/1UzeOzs