The whole point of scaling is so that the difficulty is as similar as possible relative to the number of players near the titan haha. This makes it so that the fight is appropriately challenging without people being able to zerg it to death in a matter of minutes. As I suggested (see below quote), scaling could happen only after a set number of players are already nearby to ensure it doesn’t scale down to make it too easy for smaller groups…(now who isn’t reading? 
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I think scaling is a really good idea that several games already use to address the issue of zerging that you brought up. As long as it’s still challenging enough to require multiple people and doesn’t scale down to avoid this, I see no real issue with it. Was this your only complaint?