QUOTE(BlueWaterSplash @ Jan 7 2019, 06:29)

I tried to crunch the numbers on myself just now but it's hard to decide the best way to compare. Without Spirit Stance:
Protection = 100 MP (210 turns)
Spark = 124 MP (125 turns)
Haste = 138 MP (125 turns)
Shadow = 133 MP (98 turns)
Spirit Shield = 119 MP (104 turns)
Heartseeker = 469 MP (352 turns)
Regen = 281 MP (102 turns)
Cure = 80 MP
Absorb = 119 MP
Total Mana = 1634 MP, +27 MP regen per tick
The
Wiki claims the estimated chance for Protection + Spark + Haste to proc Channeling is 362 / (1634 * 1.2) = 18.5% though that seems low to me.
Using IA5 the cost saving is equivalently 362 * 50% = 181 MP
With hardcasting the savings are 18.5% * (469 * 150%) = 130 MP
It's a close comparison and IA4 is about the same either way.
first, you're not being fair with the calculation as you don't count the possibility from total lose if you lose the gamble, at the very least you don't even count the cost you have to pay to roll the dice (spell cost to cast it).
second that's not how you work with chance calculation.
channeling chance is based on BASE not total, I'll just assume it's +100% with only abilities, so I'll use 817 as the base.
protection 100 = 100 / (817*1.2) = 10.2%
spark 124 = 124 / (817*1.2) = 12.65%
haste 138 = 138 / (817*1.2) = 14.08%
chance of getting channeling somewhere after casting those 3 is => 1-( (1-0.102)*(1-0.1265)*(1-0.1408) ) = 1-0.674 = 0.326 = 32.6%
that also means 67.4% chance you won't get channeling after casting all three.
what happened when you cast an IA slotted spell?
1. You pay for the spell cost (-)
2. you don't have to pay the upkeep anymore (+)
3. you lose any potential mana saved by IA (-)
4. you got chance for triggering channeling. (+)
let's assume IA 3-5 with protection spark and haste slotted then you cast protection, spark, and haste (in the said order) to try triggering channeling.
1. You pay for the spell cost : - 362
2. you don't have to pay for upkeep : + IA3 253.4 IA4 217.2 IA5 181
3. you lose any potential mana saved by IA : - IA3 108.6 IA4 144.8 IA5 181
4. you got chance to trigger channeling : + HS cost
HS cost is 469
IA3 469 - 362 + 253.4 - 108.6 = 251.8
IA4 469 - 362 + 217.2 - 144.8 = 179.4
IA5 469 - 362 + 181 - 181 = 107
sure, lets' multiply HS by 1.5 as it returned 1.5x,
add 0.5*HS base cost which is 0.5*469 = 234.5
IA3 251.8 + 234.5 = 486.3
IA4 179.4 + 234.5 = 413.9
IA5 107 + 234.5 = 341.5
That means you have 32.6% chance of saving between (IA5) 341.5 to (IA3) 486.3 MP
but what if you didn't trigger any channeling
that's a loss of
IA3 362 - 253.4 + 108.6 = 217.2
IA4 362 - 217.2 + 144.8 = 289.6
IA5 362 - 181 + 181 = 362
that's 67.4 % chance losing between 217.2 to 362MP
assume you do it over 1000 first round, that's
IA 3 saving 158,533.8 MP and wasting 146,392.8 MP ( avg net gain of 12.141 MP )
IA 4 saving 134,931.4 MP and wasting 195,190.4 MP ( avg net loss of 60.529 MP )
IA 5 saving 111,329 MP and wasting 243,988 MP ( avg net loss of 132.659 MP )
oh BTW, your chance of getting channeling after casting hearseeker is 469 / (817*1.2) = 47.84%
if you simply use the channeling to cast HS again, that's 469 MP for 47.84% possibility of "saving" 234 MP with nothing to lose whatsoever. that's 111,945.6 MP saved over 1000 first round ¯\(ツ)/¯
after protection didn't trigger channeling, even regen have better outlook. 281/(817*1.2) = 28.66% chance to trigger channeling
you don't have to waste anything as you're bound to cast it anyway and you already have 28.66% chance of triggering channeling.
PS : in reality I doubt you'll use the entire duration of channeled HS anyway, meaning lower mana saved, as the spell duration is fkin long even on normal cast you'll bound to obtain channeling before it runs out, and that's how it's usually happen to me.
My normal casted HS = 429 turn, channeled cast = 643 turn

2847 turn, 6HS casted, that's averaged 474 turn before casting another HS. meaning, in the end I only use ~10% bonus duration from every channeled cast, you might say I should use channeling to cast HS when it's on lower count - to maximize the bonus from channeling, but even without that, there's still 11 "wasted" channeling that ended up used for absorb as HS still have a freaking long time before runs out.
CMIIW