Ok, so heres what you do
1. Spec demonology so you can have demonic sacrifice and master demonologist
2. summon a pet (we'll use succ as an example cause she looks the best)
3. look at the little square where your buffs are that says it gives you +10% to all dmg
4. Sacrifice your succ, you should now have the +15% to shadow dmg buff on
5. (key part) Have a priest res your succ.
6. There you have it, now you have the +10% to all dmg buff, and the +15% shadow dmg buff on at the same time.
The trick to this is that for demonic sacrifice, it says the buff will be canceled out once you summon another pet, so instead of summoning one, you have someone res your existing one and it wont count as a summon. This works for all of the warlock pets.
1. Spec demonology so you can have demonic sacrifice and master demonologist
2. summon a pet (we'll use succ as an example cause she looks the best)
3. look at the little square where your buffs are that says it gives you +10% to all dmg
4. Sacrifice your succ, you should now have the +15% to shadow dmg buff on
5. (key part) Have a priest res your succ.
6. There you have it, now you have the +10% to all dmg buff, and the +15% shadow dmg buff on at the same time.
The trick to this is that for demonic sacrifice, it says the buff will be canceled out once you summon another pet, so instead of summoning one, you have someone res your existing one and it wont count as a summon. This works for all of the warlock pets.