Any way to reduce a target's Magic Resistance?

[SolemnGolem]

I'm looking through both the GURPS DF and the DFRPG books, and a fair number of creatures have MR at +4. This seems to mean that no matter how strong the caster's effective skill, the target will whiff the majority of spells cast on it.

[2021-06-22 edit: this is wrong. Rule of 16 (or 17 or whatever) applies after all other modifiers, so with arbitrarily high caster skill and similarly arbitrarily high defender resistance attribute, the mathematics will tend towards both sides trying to roll against 16 in a quick contest. In other words, defender (who wins ties) has a 98% chance of rolling 16 or below, and attacker must exceed that margin of success, which roughly eyeballed at 15 or below is 95% chance for something close to a 3% slight favoring of defender per Quick Contest. It's pretty close to 50:50 rather than my initial assumption of a 98% likelihood of defender wins all resistance rolls.]

Is there any way to bring down the MR of a target discussed in any of the books?

I'm happy to houserule my own arcane time-consuming workarounds, but just wanted to check with the hivemind first.

As an aside, D&D had a (perhaps somewhat counterintuitive) method where a magical spell could lower a target's MR.

Edit to summarize new findings as of 2021-06-22:

1. The MR penalty applies to both sides of a Quick Contest Roll for resistance, wherein Rule of 16 is applied last of all. E.g. most Mind Control spells will allow a Will resist roll. This means MR of 4 penalizes the caster's roll at -4 and aids the target's roll at +4... but like any Quick Contest, margin-of-success is relevant to the final outcome.

2. Therefore, a caster with a sufficiently high adjusted casting skill level could still be rolling at 16 (see Rule of 16) and the target would still be rolling at 16 as well, as the Rule of 16 is applied after all other relevant modifiers are applied (including the plus/minus for MR). Since both characters are rolling against the same target number, and defender wins ties, the actual chance of attacker success is slightly lower than 50%. While less than a majority, it is still a decently high chance of success... and as the caster's and the target's relevant stats get higher and higher, it trends more towards the same opposed roll to meet the same target number.

3. It's possible to remain within DFRPG player character generation rules-as-written and still have a BBEG with a decent chance of spellcasting success against canon monster levels of MR and attribute resistance. If a GM bothers to even stat the BBEGs† then effective skill levels of 30 to 34 or higher are needed for some DFRPG enemies with MR 10 and decently high Will or HT scores. For a BBEG that is assumed to have been created in accordance with the DFRPG player character standards this is achievable with an IQ of 25, Magery of 6, and pumping lots and lots of skill points into the relevant spell(s). A "once in a generation, caster of legend who has practiced this spell over and over through the centuries so that they're the best this dimension has ever seen at casting it" could fit this bill, flavorwise.

4. Other solutions are eminently workable Others including Dr. "The Word of GURPS" Kromm have kindly shared their own calculations for Affliction (or other advantage-based) MR lowering, and also for spells and items that lower MR.

Hopefully this summary helps bring this thread's discussion state up to date in case any newcomers stumble across it.

† assuming that the GM even cares about this, which I superficially do, depending on my mood.

[AlexanderHowl]

No, that is really the point of MR, it is one of the reasons why magic is relatively cheap.

[Anthony]

There aren't any practical methods of doing so (Shapeshift Others will remove racial MR, Great Wish can remove any sort of MR, but I wouldn't call either one a useful option).

[David Johnston2]

Originally Posted by SolemnGolem

I'm looking through both the GURPS DF and the DFRPG books, and a fair number of creatures have MR at +4. This seems to mean that no matter how strong the caster's effective skill, the target will whiff the majority of spells cast on it.
.

How do you figure that? While I've never played DF as I understand it 250 point characters are standard. That's a lot of CP to spend on your wizards so any thrown spell you are seriously relying on for offense really should be upwards of 20.

[Refplace]

A magical method of reducing MR would have to go against it.
Game wise it just means some monsters require some different tactics and maybe special equipment to deal with.

[corwyn]

My wizard has a base spell skill of 20, accessible as a starting DF wizard. He can break MR 4 just fine.

Also, missile spells, particularly combined with Great Haste.

[Rupert]

Originally Posted by corwyn

My wizard has a base spell skill of 20, accessible as a starting DF wizard. He can break MR 4 just fine.

-4 to skill, along with any range penalties, and +4 to the resist roll. Even with no range penalty it only takes Will-12 to reduce the mage's odds to 50%.

That suggests that if MR-4 is fairly common in a DF game, skill-20 with their favourite offensive spells (if they're resisted) is a starting skill level, not a good level.

[corwyn]

Originally Posted by Rupert

-4 to skill, along with any range penalties, and +4 to the resist roll. Even with no range penalty it only takes Will-12 to reduce the mage's odds to 50%.

That suggests that if MR-4 is fairly common in a DF game, skill-20 with their favourite offensive spells (if they're resisted) is a starting skill level, not a good level.

I guess that's a valid point, but I just took a spin through DFRPG Monsters and found almost nothing that isn't MR 0, 6 or 10. So either 0, or clearly not to be dealt with magic. Is it a higher percentage in regular DF?

For the latter, I'll cast Might, Grace, or Great Haste on one of the meat shield melee machines. Generally more efficient. There are a lot of ways to contribute without direct damage. Also, Blink Other, Command for helping their defense.

Bottom line, if you can't break their MR, find another spell to help with. I consider that a feature, not a bug.

[Anthony]

Originally Posted by corwyn

My wizard has a base spell skill of 20, accessible as a starting DF wizard. He can break MR 4 just fine.

I suspect that was representative, though between range penalties and the fact MR both reduces skill and increases resistance rolls, skill 20 is frequently going to be under 50%.

Actually looking at DF:M

• Eye of Death: MR 10. Requires skill-30 to tie vs IQ, 31 vs HT.
• Foul Bat: normally none, some have demonic leaders with MR 10.
• Mindwarper: MR 6; requires skill-30 to tie vs IQ, 24 vs HT.
• Mold: MR 4; requires skill-24 to tie vs HT (mindless)
• Ogre: MR 2; requires skill-11 to tie vs IQ, 17 vs HT.
• Pudding: MR 5; requires skill-14 to tie vs IQ (but immune to mind control), 23 vs HT.
• Sphere of Madness: MR 10; requires skill-30 to tie vs IQ, 34 vs HT.
• Watcher at Edge of Time: MR 6; requires skill-22 to tie vs IQ, 24 vs HT.

[coronatiger]

You could build an Affliction with Negated Advantage.