Nemesis isn’t the strongest attacker. It just has the Phoebe heal circles with an acceptable amount in mid to long range area damage that Phoebe doesn’t in base attack form. In that sense, sure, it could be considered op compared to her. I really don’t think it’s game breaking for the cost, or the nature of free to plays, longer players get better stuff. As for the other non heal abilities, they are so random you can’t really count on, and unlike Phoebe you can’t use pal flute for a gain. Unless they fixed it recently, you’ve nerfed yourself.
I’m of a mind it’s the other stuff you’re all using in mass that needs to be considered too, if we’re going to be honest about this perceived issue. The spells, units, and boosts aren’t the same by a long shot, some one hit, while others struggle to take stuff down (before a heal or howl hits), including some spells with 60k in armor boosts against their weakness. Some of the more powerful boosts are kind of a reward for doing well as a team, so I mind them less, but can’t deny it would be fairer to us all if these things were just built in as we leveled them. For the better earned boosts anyway, they aren’t a guaranteed constant to a team playing fair. You know who you are, and the honest players are proud of you.
For me it’s parts of a whole that is the debatable problem. Even the things you’re all overlooking as no problem matter. If you think you’re unstoppable with it, try joining a lvl 30 team, and using spells and units outside of your suggested or video watched setups, and see if you can still hit those top 50 ranked ones reliably like you used to lol. Not saying it’s impossible, but you should notice some more challenge.
As for the last reason (I can think of readily) you are seeing less fails, several towers took a hit in power last few updates. A large part is you no longer have the same dps levels to stop things with newer additions, till they level them again. You can beat the dragon with some adjustments, not every time, nor should you, and most of us are in the same boat, leveling stuff we never touched much because it wasn’t great before.
My concluding point is, we all need to think broader on this stuff rather than breaking one thing, and leaving all the other stuff alone. Balance doesn’t work that way.