Not the answer you're looking for but it might help you out. If you have him, I'd try subbing out a Holy Fire for Prophet Velen. Mainly for the surprise ten damage Mind Blast. I could be wrong, but I would assume it's hard to get a lot out of Holy Fire in Aggro Priest.
Then again, I can see it being great for removal while extending your life too. I would say it's worth experimenting, especially if you keep having trouble in the late game. You know your deck better than me though and maybe having two high cost cards would break the deck. I just personally love the combo myself because it feels like the animation happens so fast when you kill someone with it.
people have mentioned velen to me, but, the problem is this; aggro priest only works if you can win t6-t9. like face hunter, basically. you CAN'T save cards for a future combo, because the only card draw is PWS (which is OK, but, again, only because you're maximizing mana on all turns). holy fire is not efficient, but, it's used like this;
opponent has 11 health on turn 5. use holy fire turn 6, double mind blast on turn 7 to win. or holy fire to stall one turn to drop boom the next then go lethal. i've toyed around with the idea for a while because it's obscure and no one else has even really tried it, but late game combos kill it without card draw and, like face hunter, introducing card draw destroys your win condition.
like brann; brann, theoretically makes a double shadowbomber hand hit for 12 face damage on turn 5. which is absolutely bonkers. but you can't rely on a 1 off card, you can't build a deck like aggro priest around it, because if you do, the deck will be crap every time brann hides. i know it needs a tinker or two but adding late game is really working against the idea.
as the deck is, it hard counters secret pally and wrecks face hunter.
as of now i'll drop the worgen for a second owl but, i'm not totally convinced that's the best option because half of the win condition of this deck is getting massive early board and swinging for face; the second half of the win condition is insane t6-9 damage that can usually bypass taunt (mindblasts do 2.5x mana value face damage, leeroy, arcane, holyfire, you can easily do double digit face damage on turns past 6)
