Okay fact you might not be aware of.
The slime queen cannot consume a defender (using Defend)
The Dragon boss Last Stand only applies when your drain happy otherwise it The dragon boss with 2 pile of gold (that have taunt effect and thorn gimmick)
Factory is easy you need dragon throat and grow gun with the temporal watch and you can defeat the factory no problem as one the factory is out the bot do not respawn and this also affects the Mad Scientist boss fight.
Phasing is fine only 2 enemies in the game has Phasing. Red Bot and shadow stalker which I assume you were fighting. Shadow stalker only show up if you are drain happy and have broken bosses or alot enemies.
I don't feel like you actually read my criticism if your answer to some of this is "the 2nd boss is easy if you have 3 legendary items", which was something I directly criticized as bad design for over-centralizing around the items
Similarly, bosses shouldn't be insanely obnoxious just because you chose to use the mechanic the game is designed around