Huh, I was by myself on the last day of ToT and the EBs did focus on me solely instead of my robots. Every single one of them. I don't spam attacks either since my End goes down quick when I do. I was fine with the mummy by hovering and he only got my health down to half one time but I never had to summon Maintenance Drone since he never attacked them. Same happened with my mercenaries/traps. I didn't think much of the behavior when i can make them dance around caltrops as my guys whittle them down. Playing in a league they got pulled off of me all the time. I survived solo-wise with all my MMs. Not saying anything either way but that was my experience. /shrug
Anyways, I loved all the new EBs. Whoever designed them did an awesome job and they were a nice surprise this season.