^This! Sunreaver always died far too early for me. So if you have the Pocket Cannon I recommend using Jane's strategy. Easy and oddly satisfying to watch the little thing take out Deathscreech almost on its own. Took another two arcane blasts to finish the fight.
2-Pet Strat :
Lil' Bling - Blingtron Gift Package (keep restarting fight until this hits) > Make it Rain > Inflation (ideally you want two turns of Inflation before dying)
Stonegrinder - Clean-Up > Thunderbolt > Screeching Gears for the kill. :P
This. Very this. 4x Arcane Shot then Explode - got it down to 350hp. Still used Lil' Bling in slot 2, though I think any pet should be able to finish it off. I used Blingtron Gift Package and Inflation.