New life force card life speaker helps this deck out a lot. Also this deck can utilise the market nicely to fetch key cards such as katra. The combo is to have an auric interrogator with lifesteal and more than 4 attack with a katra on board. Then your auric interrogator will activate katra at the end of every turn. Before the only good way in xenan to give auric interrogator lifesteal was lethrai falchion and they are still 2 of these as insurance plus a Titan/blistersting wasp with falchion can win you the game anyway. If you draw your auric interrogators before you draw your life speakers don't worry because the inspire from lifespeaker is also activated via dark return and incidentally the market aswell. Since making the deck I have won 10 gauntlets in a row in master tier. Haven't played this in ranked yet but I used to play something similar in set 2 to reasonable success so I'm sure with a few tweaks accounting for the additional removal you may see on ladder this deck could also be semi-competitive.
(I used naptime's suggested edits - the extra SST and Banishes seemed strong, and SSF won the final boss battle for me).
Suggested changes: -2 Lunar Magus, -2 Lethrai Falchion. +3 Banish. Move 4th SST to main deck, replace with Striking Snake Formation in Market.