Like most have already stated, this is a really bad trend to set, the only thing that makes assault battles worth investing in is the expected long term roi, if your just going to phase out the assault battles as new ones are created this means you never recoup your gear investments so why even bother playing them. There's already so much lag time in between events and things going on in this game you could have easily just fit one more assault battle into the mix if you really wanted to. Even that is eventually flawed though because if you continue to add them then eventually there will be too many. Also one of the biggest things this game is struggling with is new player acquisition, and so your brilliant idea is to keep making end game content instead while taking away new player content making it even more impossible for them to ever catch up instead of fixing grand arena by putting it back the way it was so people can have fun playing it again, and since we all know you're whole reason for changing it was too many crystals going out and not enough incentive for players to build out their rosters, just provide gp tiered rewards so getting kyber 1 in the 1-2mil gp bracket awards less crystal than say kyber 1 in the 8-10mil bracket or whatever. That would give people incentive to build their rosters but fix the garbage that is happening now that makes gac so lack luster in it's current state. You could also have added a new game mode to offset the income lost from the old assault battles if you wanted to start phasing them out. You could make it something along the lines of conquest style and run it during the month lag between conquests. This way noone is negatively impacted when one fades into obscurity but it still gives you room to continue to develop new content for late mid/end gamers.