Ion Cannons
Ion cannons are really, really fun on the offense. However, on the defense, they can feel a little overwhelming. Usually your opponent has set up ion cannons because they have already devastated your army, or, they have gotten really sneaky 
It would be nice if there was a neutral weapon that functioned as an area 'shield' that would protect from ion cannon blasts, for a short period of time (a few seconds) in order to give your team a chance to respawn/respond to a threat. I realize it would take a bit of balancing to get this functioning properly, and prevent a 'turtle' strategy from becoming overpowered. However, I feel that giving a defending player who has gems to spare a chance would reduce the level of 'feel bads' from having 5 ion cannons blowing up your node.
Comments
My problem is that once Ion Cannons come into play, they have a really high health pool and 3 armies blocking them. That means that unless you wipe every member of all three opposing players, with the range Ion cannons have, they'll decimate your base quickly and cruelly. It also snowballs very quickly once they come into play. I love the smaller Ion Cannons, they have a good balance of range and hp, but the bigger ones... all you have to do is get somewhat close to the enemy's Nexus, plop two or three down and stave off the enemy for a little while and you win. It's very hard to come back from that sort of rush play.