Miscast test results.

[roguelikedev]

Recent threads regarding the value of Sif Muna's miscast effect protection made me curious; in particular, Galehar seemed pretty sure that you could suffer serious miscast effects from failing something at 'excellent,' which I can't remember ever happening to me. So, I made a wizard character and cast some spells. The character had 18 in all skills and 26 INT; both spells cast at 'great,' mainly to save time in actually miscasting them.

Necromutation (8th level necromancy/transmutation):
very lightly contaminated * 13
slow (15 and ??? rounds) * 2
nothing * 2
bad mutation * 1
agony * 1
drained for 8316

Lehudib's Crystal Spear (8th level conjuration/earth):
very lightly contaminated * 14
nothing * 3
yellow glow (1 mutation) * 1
blasted (11 and 33 damage) * 2

Of 40 total failures, we see two individually serious mutations, plus three effects (slowing and agony) with a high potential to be serious. This obviously wasn't a particularly authoritative test, but was good enough to convince me that miscasting a reliable spell can still hurt; given the total number of casts required to produce these bad effects, I'd still refrain from calling miscast protection a compelling reason to worship Sif Muna, but it's at minimum a solid perk.

[Kate]

Conjurations and Earth magic have very weak miscast effects anyway, even on severe miscasts, but Necromancy and Transmutations ones are particularly nasty so yeah, that's a case where the miscast protection is genuinely very handy (I managed to get Dragon Form on a DrTm by the end of Lair, using Sif's miscast protection to be able to cast it much earlier than otherwise would've been safe, for example).

[theropod]

The severity of a miscast is of course highly situations. For Necromutation, arguably only the mutation was truly bad. As for slowing and agony, one rarely casts Necromutation in a dangerous context: one casts it once in relative safety, and then use Extension.

LCS on the other hand is a combat spell, and the blasted for damage miscast could be quite relevant on fragile conjurations based builds. (Although in the combat situation, the worst consequence of miscasting LCS is likely having spent a turn and 8 mana for nothing.)

[MrMisterMonkey]

Extension doesn't exist