Teemu
Hero
I didn't read the whole thread, but I think Pillars of Eternity 2: Deadfire had a really good solution for control effects and bosses. In a nutshell, if your ability would apply the most powerful debilitating debuffs on a powerful enemy, they downgrade the severity of the debuff by one step. This of course requires the entire system to work on the concept of debuffs working in degrees of severity. For example, in Deadfire, Stunned is the harshest of its category, followed by Dazed (can act but hindered power), and finally by Staggered as the least powerful (slightly penalized). If your ability would inflict Stunned, a resistant enemy would instead be Dazed. There's no usage limit on the enemy's ability to downgrade the debuff. Some enemies even downgrade by two steps within a particular debuff category.
If D&D worked the same way, there would be no issues with control spells feeling weak vs being too powerful. Even if the enemy couldn't be Stunned, you would still debuff them with your ability. You could of course adjust how this would work in a tabletop game. For example, maybe the enemies are resistant to the debuffs while they're at a certain HP value and once they're low enough, you could inflict even the stronger debuff on them.
				
			If D&D worked the same way, there would be no issues with control spells feeling weak vs being too powerful. Even if the enemy couldn't be Stunned, you would still debuff them with your ability. You could of course adjust how this would work in a tabletop game. For example, maybe the enemies are resistant to the debuffs while they're at a certain HP value and once they're low enough, you could inflict even the stronger debuff on them.