MR certainly does not help against SCs (Stellar Cascades, dummy
), but with E9 bless the extra armour helps a bit and extra reinvigoration even more. Only problem with SC is that the AI won't cast it, preferring Paralyze even against MR 30+ opponents. Which is plain silly.
IMHO the AI statistical analysis shouldn't be just about the expected return (effect * probability), but should take variance into account. Even taking just median result would help against high-effect outliers that make AI cast paralyze on night-immune targets.