Hi Marathol,
Hm... For Mind Sear...
as baseline: 1652
as shadowform: 2064 (25%)
as searing insanity: 4128 (100%)
cop baseline: 2312 (40%)
cop shadowform: 2890 (25%)
cop searing insanity: 5780 (100%)
1652 * 1.4 *1.25 *2 = 5782
That's how the damage multipliers work.
Is that what you are asking?
.................
The way your post is worded, it seems like you're just wanting to know what level 45 talents to use on what fight.
This is basically the logic I use to determine that.
1. Are there two or more targets up for the majority/entirety of the fight?
Yes - Surge of Darkness. Ex: Twin Ogrons, Hanz & Franz, Iron Maidens
No - continue
2. Will I cast Mind Sear during this fight in such a way that it is necessary?
Yes - Insanity. Ex: Tectus, Thogor, Beastlord, Kromagg, Blast Furnace
No - continue
3. Can I stand still, or minimize movement to the point that I will not interrupt DoTWeaving, and is the boss targetable for the entirety of the fight, and are there no/almost no adds during the fight, and do I have the tier 17 4p set bonus?
Yes - Insanity. Ex: Gruul, and a bunch of fights in Highmaul
No - Use Mindbender for all else. Ex: Oregorger, Blackhand, Flamebender
4. You could probably put it in one of those flowcharts or something and it would catch like 99% of the fight types.
After we drop T17, the 3rd question might get taken out of this, so that the only time you'd take insanity is if you plan to cast Mind Sear. I will need to play around with simcraft and higher ilevel gear to see if the damage differences still hold. At current/lower gear levels, Insanity isn't beating Mindbender out for single target without t17 4p set bonus. I saw a few sims that were showing DoTweaving beating Mindbender in T18, and if it does it's because Shadowfiend and Mindbender's damage is brought closer in line with each other due to T18 2p set bonus. Right now, Mindbender is a pretty significant damage increase over shadowfiend, due to the reduced CD.