Quote Originally Posted by Silly Name View Post
Funnily(?), this transplants a common videogame problem into D&D. If you have ever played Final Fantasy or similar RPGs, you'll be familiar with the dreaded useless powerful spells. Stuff like four to five flavours of instant death, poison, time stop, silence and the like: all powerful conditions you can impose on your enemies... Except when it matters. Bosses are almost always resistant to all those nifty powers you can get, while the creatures susceptible to them aren't worth spending the resources on.

Now, this isn't as bad because usually in D&D you can still get some worth out of your class features by directing them at minions or in other encounters, but as we approach higher level the resemblances grow. If the enemy can just auto-succeed at his save against your only ninth-level spell for the day, you will want to pick a ninth-level spell that doesn't allow for a save.

I am perfectly cognisant of the balancing factor of Legendary Resistance, and so are my players. It simply feels bad, especially when you consider that casting a spell that allows for a save means the player has already committed to the chance of failure, just like how the party's fighter knows he could miss on his next big attack. Seeing the boss monster fail the saving throw and then just shrug it off isn't really a cool thing. There should be a more elegant way to address the problem of powerful Save or Suck powers shutting down a boss.

Hell, probably outright immunity would be less feel-bad. "The lich's centuries of research in the deepest arcane secrets have granted her the ability to be unaffected any illusion and charm spell of less than sixth level" is far more interesting and better communicates the lich's powers than "the lich can say 'no' to three saving throws per day".
So here's the thing about those 'useless final fantasy spells'.
They aren't useless, there's usually a logical application for them, it's just that figuring out which enemies are weak to which spells is more effort than just mashing attack until the combat is over.