D&D 5E (2014) Sell/unsell me on Magic Resistance and Legendary Resistance

[Redbadge]

One could potentially come up with a list of "lesser effects" for Legendary Resistance to provide. What I mean is, rather than "Hold Monster didn't work at all," it could be "Hold Monster didn't succeed in paralyzing the creature, but it slowed its movement for a round."

Maybe the next couple of attacks against the creature automatically deal max damage. Or the creature's next attack deals minimum damage. Or the creature loses one of its legendary actions for the round. A lot of them would default to "disadvantage for a round," but even that's better than accomplishing nothing.

It'd require the DM to create this list in advance, but once done, it's done, with only corner cases to be adjudicated on the fly. It might or might not vary per creature; DM's prerogative.

How about: Legendary Resistance (3/day). If the creature fails a saving throw, it can choose to succeed instead. If it does so, it takes damage equal to five times the level of the spell, or 5 times half the level of the effect or source if the saving throw was the result of something other than a spell.

This way the spellcaster would still be contributing to the ultimate goal, even if something like hold monster was ignored. In addition, the players can still see the spell had some effect, as the creature had to use at least some energy or vitality in ignoring it/throwing it off. And this method doesn't require a list or adjudication of corner cases.