Something that I've noticed becomes a frequent issue when making events is that there are a lot of situations (or have been) where it would be a major quality of life if the GM could control their mobs while they play their event character. This is where I propose the concept of being able to make custom mercenaries for themselves. Basically, the idea is that they would be able to put mobs they make into their own mercenary list so they can fight players with these mobs active. This is the most straightforward way I can think for it to work, but if there's a better idea, that would be great.
I've noticed that these mobs, when created, will often need some kind of resistance/weakness adjustments in order for them to be interesting to fight against. Or challenging. This is where I propose that they are able to have their resistances to specific damage types be adjusted, manually, without having to go through a large list of skills/passives just to make them resistant/weak to something in particular. Currently, you're not able to put in specific numbers for their damage type resistances, so I think this would be a vastly appreciated quality of life.
TEMPORARY MOB LOADING
Sometimes, the custom mob the GM is playing will fight alongside some other event character played by someone... that isn't a GM, so they unfortunately cannot modify their character in the same way the GM can. I'm not saying people should be able to edit their stats to infinity, but I think it'd be neat if event tools allowed you to temporarily load a custom mob on a player. I'm not sure how difficult this is to implement, but the way I envision it working is that the player in question loses their custom mob state once they log out from the game (or unless the GM manually disables it)... I think that this would also be a nice quality QoL for events.
MANUALLY ADJUSTING HP AND FP
As far as I know, Event Tools don't allow you to set a specific HP/FP amount for a mob. This would be nice to have too!
These are my ideas. I'm open to criticism, and I don't expect any of them to be guaranteed to get in, but I felt like putting them out there.