I looked through the suggestions list as much as I could and I didn't see this mentioned, so I apologize if this is yet another repeat of an old suggestion or complaint.
I've been in a couple of escalating games in which a player has gotten him/herself a set and then deadbeated two turns in a row, allowing everyone else to turn in their sets, thereby increasing the value of his/her set. Then on turn three, not only does the deadbeater get three times the deployment bonus (which I realize is being taken care of already), but they ALSO get a very valuable set of cards. Recently, an excellent assassin game I was playing in was really ruined by this strategy in my opinion. A player who was on the ropes but being protected by others because we didn't want to lose because of a deadbeat showed up and smoked us all by pounding across the map with 20-something armies. Game # 242114.
I just thought it might be good to install a lock on set values at the set value on a deadbeated turn. So, let's say that I get a set and on my next turn I could turn that set in for 12 armies, but I deadbeat. I think that I shouldn't be able to hang onto that set for two more rounds and cash in when I decide to rejoin the game for, say, 30 armies. Obviously in most cases, I will have been attacked during the two rounds that I was missing, but in assassin games, the participating players MUST protect deadbeaters or they will lose the game. So, at the very least, I would suggest this kind of locking of set values for assassin games.