Iskenderun's Mystic Blast & Armor

[hannobal]

I'm crawling with GrEE at the moment, and i've got both Stone Arrow and IMB memorized, 1% failure rate and hungerless.
They seem to do about comparable damage at max power.
IMB has longer range and it can explode, but also the cost is 1 MP higher.
Anyway i'm thinking about ditcing one of them, as they both fill the purpose of mid-level single target damage.

I know Stone Arrow damage is reduced by armor, but what about IMB?

Wiki says it does physical damage, but that's about it.
http://crawl.chaosforge.org/Mystic_Blast

[Siegurt]

Yes, it's also reduced by armour.

For comparison IMB does
2d(6+(Power/6)) damage
and stone arrow does
3d(5+(Power/8)) damage

However it also only takes conjurations to make IMB more powerful whereas it takes both to make stone arrow more powerful. Stone arrow also misses more, and as you've noted doesn't explode for splash damage.

[stickyfingers]

And IMB has more range. Unless you're training only Earth for some specific spells, IMB is strictly better.

[Hurkyl]

Yes, it's also reduced by armour.

For comparison IMB does
2d(6+(Power/6)) damage
and stone arrow does
3d(5+(Power/8)) damage

However it also only takes conjurations to make IMB more powerful whereas it takes both to make stone arrow more powerful. Stone arrow also misses more, and as you've noted doesn't explode for splash damage.

To make the formulas more transparent:

IMB averages 7 + P/6 damage, or roughly 7 + 0.166 P damage. That's 1.75 + 0.042 P damage per MP. It maxes out at 23.67 damage (average), or 5.91 damage per MP.

SA averages 9 + 3P/16 damage, or roughly 9 + 0.188 P damage. That's 3 + 0.063 P damage per MP. It maxes out at 18.38 damage (average), or 6.13 damage per MP.

(numbers are before adjusting for enemy AC, of course) If you have both at max power, it seems clear that you should go with IMB even before taking into account its other advantages. Prior to that point... I have no idea how spell accuracy works, so I can't offer any sound advice.

(FWIW, Stone Arrow is quieter than IMB, even when the latter doesn't explode)

[hannobal]

Thanks for the info. I'll get rid of stone arrow with scroll of amnesia.

I suppose armour is applied to Orb of Destruction and Lehudib's Crystal Spear too.
With those spells it must be less of a problem due to higher base damage though...

[rebthor]

Thanks for the info. I'll get rid of stone arrow with scroll of amnesia.

I suppose armour is applied to Orb of Destruction and Lehudib's Crystal Spear too.
With those spells it must be less of a problem due to higher base damage though...

Yes, as well as pretty much every other conjurations. AC is also applied to LRD explosions multiple times.

[Lasty]

Armour is applied to almost everything. According to learndb: "The only player-castable damage spells that ignore AC are freeze, refrigeration, sticky flame, static discharge, pain, vampiric draining, and agony." Add torment and hellfire to that list, and you've got nearly everything in the game that ignores AC.