I wasn't aware of this undocumented feature, so I spent a few minutes on the dummies and in the log browser to do some more research on it. My findings:
Sacrificing my minion in combat granted ~100 Demonic Fury, however I wasn't always able to get the fury gain and I would need to do more testing to figure out the exact conditions needed.
The majority of my testing after confirming a fury gain went to figure out how to best abuse it. I used the felguard due to his ability to instantly get in range and deal damage, I also tested with the imp but I couldn't reliably get the fury gain from him. The questions I wanted to answer is: 1) Is it worth starting combat with a pet out, and 2) is it worth resummoning a pet with Demonic Rebirth?
The logs from which I made my calculations:
http://www.worldoflogs.com/reports/6...log/?s=45&e=88
And the log query to filter the interesting parts (my pet Rivinshril and spells affected by GoSac):
Code:
[{"eventTypes": [1], "actorNames": ["Rivinshril"]}, {"spellNames": ["Fel Firebolt", "Shadow Bolt", "Soul Fire", "Touch of Chaos", "Hand of Gul'dan", "Grimoire of Sacrifice", "Summon Felguard"], "eventTypes": [1, 6]}]
In all my calculations I normalized crits to normal hits to remove some of the RNG (except Soul Fire which always crits), however I didn't unequip gear with procs which means those procs can have skewed the numbers in either direction.
To answer my first question, yes it's definitely worth it to start combat with a pet out. On the pull I did 29827 damage with GoSac spells before gaining the buff, which is a loss of 7456.75 damage, in return my pet did 106,327.5 damage on the pull. GoSac is off the GCD and costs no mana which means I lost nothing from using it after the pull but
I gained a total of 98,870.75 damage and ~100 Demonic Fury.
For reference, the starting rotation I used was HoG -> Corruption -> Imp Swarm -> Dark Soul/Blood Fury/GoSac -> HoG -> Doom -> Touch of Chaos spam.
The second question requires a little bit more thought and calculations and I'd encourage any theorycrafters to try figure this out as I'm not very well versed in this stuff myself. This part starts from when I summon a new felguard at the end of the Demonic Rebirth buff, which conveniently is at the same time as my DS runs out and the imps from Imp Swarm finishes up. At this time my pet will be out for 10 seconds until the cooldown of GoSac is up again. As for the damage numbers I doubled the wild imp damage in this time frame as I lost one imp from not having a UVLS proc on the pull.
During the 10 seconds of not having GoSac I dealt 741,811.5 damage with GoSac spells, a loss of 185,452.875 damage. In the same duration my pet dealt 219,318.5. In total I have
a gain of 33,865.625 damage and 100 Demonic Fury, but at the cost of ~1.75 GCD (Summon Felguard + Life Tap to make up for the mana loss). I won't make any conclusions of whether the second pet summon is worth it or not as I'm not absolutely certain about the worth of the DF and GCDs, but my intuition tells me it's a small gain.
A third question that could arise would be whether it might be worth pet twisting later in the fight.
Edit: I didn't use Felstorm in this test as in my first tests I tried using it on the pull but experienced that I then wouldn't gain fury from the second Sacrifice, I then forgot to try using Felstorm during the second summon.