Ok, because many people said it's not possible to "spam" HL, although I'm doing it for most of the time atm, I tried to calculate wether it's possible or not.
I'm no math genius, so feel free to correct me if you find any errors (especially on the part factoring in the effect of divine illumination).
First of all, I 'd like to say the term of "spamming" probably is a bit misleading. Nearly every encounter does not allow you to stand in one place the whole time, mashing one button. So I've chosen three examples for calculations:
1) Casting one HL every 2 seconds (as an example of "pure" spamming)
2) Casting one HL every 2.5 seconds (as an example of spamming in consideration of lags and minor movement)
3) Casting one HL every 3 seconds (probably the most realistic example)
I'm using my stats for these calculations (129 mp5, 30% crit raid buffed, 11k mana raid buffed) and I'm assuming a fight length of ten minutes (600 seconds).
I also rather like to see illumination as a reduction for spell costs than a way to gain mana.
And I assume casting of HL R 9 (660 mana), which is the rank I personally use most of the time.
First I'll calculate the overall manacosts of casting HLR9 for 10 minutes and then subtract the mana saved through illumination:
1) Casting HL every 2 seconds -> 300 casts a 660 mana -> 198000 mana x 0.7 (30% cost reduction through illumination) -> 138600
2) Casting HL every 2.5 seconds -> 240 casts a 660 mana -> 158400 mana x 0.7 -> 110880
3) Casting HL every 3 seconds -> 200 casts a 660 mana -> 132000 mana x 0.7 -> 92400 mana
So these are the amounts of mana you'll need over the course of said 10 minutes, now let's look at the possibilities of gaining mana:
- 129 mp5 from gear -> 15480 mana over 10 minutes
- Talasite Owl assuming I'll use it two times thats -> 1800 mana
- Insightful Earthstorm Diamond (2% procchance, procs on everything, even buffs such as "light's grace" which results in an overall procchance of 4% for HL casting. Restores 300 mana/proc) will restore different ammonuts of mana for each example:
1) 12 procs a 300 mana -> 3600 mana
2) 8.8 procs a 300 mana -> 2880 mana
3) 8 procs 2 300 mana -> 2400 mana
- Major Mageblood -> 16 mp5 -> 1926 mana
- Brilliant Wizards Oil -> 14 mp5 -> 1680 mana
- Blackened Sporefish -> 8 mp5 -> 960 mana
- Manaspring Totem (skilled & tire 4 bonus) -> 45 mp5 -> 5400 mana
- Manatide (assuming the shaman has 10k man and will use it 2 times) -> 4800 mana
- BoW -> 49 mp5 -> 5880 mana
- Shadowpriest @ 1k dps -> 300 mp5 -> 36000 mana
- Spellsurge (approximately 10mp5 and 4 people in my group are using it, so 40 mp5) ->4800 mana
- base manapool -> 11000 mana
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That's 93246 mana for example 1), 92526 mana for example 2) and 92046 mana for example 3 till here. Now you can still factor in manapots, demonic runes and maybe a flask of mighty restoration:
- Superior Manapotion restores 2400 mana on average, let's say i'll use 4 -> 9600 mana
- Demonic Rune 4 times, 1200 mana on average -> 4800 mana
- Flask of Mighty Restoration -> 60 mp5 -> 7200 mana
-> 21600 mana in addition to above numbers
Divine Illumination:
Usable 3 times in 10 minutes so the effect of it will last for 45 seconds overall, crits during DI will let you actually gain mana:
Example 1) 22.5 casts under the effect of DI -> 7425 mana saved
6.75 crits during this time @ 30% critrate -> 2227 mana gained
[top]> 9652 mana for my overall manapool
Example 2) 18 casts -> 5944 mana saved
5.4 crits -> 1782 mana gained
> 7726 mana for my overall manapool
Example 3) 15 casts -> 4950 mana saved
4.5 crits -> 1485 mana gained
[top]> 6435 mana for my overall manapool
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Conclusion:
1) (casting HLR9 every 2 seconds)
138600 mana needed, 102178 mana available without, 123778 mana available with pots/runes/flask
> not possible
2) (casting HLR9 every 2.5 seconds)
110880 mana needed, 100252 mana available without, 121852 mana available with pots/runes/flasks => possible
2) (casting HLR9 every 3 seconds)
92400 mana needed, 98481 mana available without, 120081 mana available with pots/runes/flasks => very possible
So overall: If your thinking about "spamming" in the way of just chaincasting every 2 seconds, it's not really possible to do so over 10 minutes. On the other hand, if your thinking about "spamming" in the way of casting as much as possible tanking into account lag and that nearly every encounter forces you to move sometimes, it's very possible.