I've been trying to climb using Gala priest this month, and I'm using a pretty standard deck (Gala Priest Deck). I'm barely hitting 40% win rate, in large part to going 0-22 vs other priest decks (including mirror). I've watched replays, videos, etc. and I'm stumped at this point. Is there a specific mulligan strategy vs other priests? Should I be playing more aggro vs other priests? Friendly feedback or guidance would be helpful. I am pretty close to average win rate when I play using other decks (token druid, highlander mage, gala rogue for example), gala priest is just frustrating the heck out of me.
The mirror will almost always go to fatigue and will generally be decided by who can generate more value overall. Gala priest has a lot more healing/removal than burst damage so you will never kill your opponent with tempo play. Therefore it is all about value. You should try to play your Galakrond as fast as possible so that you can start generating value from his hero power. Apart from that it is heavily RNG-based. Getting Reliquary of Souls from an invoke is pretty great and stealing your opponent's prime (with Shadow Madness for example) is the nuts. Getting a random EVIL Conscripter into a random Draconic Lackey into a random powerful dragon is also the nut. Furthermore, you should also hold back on playing Murozond the Infinite and Soul Mirror until the moment they can generate maximal value Finally, regarding the deck you posted, having only 1x Sethekk Veilweaver and 1x Shadow Madness is probably a mistake as both are kind of key cards. The first is a great value generator and the second can effectively kill 2 enemy minions, sometimes stealing their prime in the process
I would keep Mindflayer Kaahrj, it can also create value, can even do some nuts combos (for example against Highlander Hunter you can play Kaahrj on King Krush, cast Penance on it and get an 8/8 with charge:P ) I'd replace Madame Lazul instead, also value-generating but less than Kaahrj I think.