These are the save or dies and save or sucks. Yes, they are cool in theory, but they are not fun for the player who gets hit by them.
That means paralysis, panic, mind control, and of course instant death. I think anything that makes any player sit out the rest of the fight is generally a bad idea unless used very sparingly. But many of these are not fun for the players. They are all very different in looks and behavior out of battle, but when fighting starts, it's hacking with swords until one side runs out of hp. I am currently working on a monster book for my homebrew setting and noticed that a lot of the creatures I have really just attack once per round to deal hit point damage.
