Like every other Katra deck, the goal is to use Katra's effect of a free unlock potential every time you gain life to make 20/20s and win the game. Sanc Priest, Seeker, Slug, and Water of Life are the main ways of triggering Katra. You also have Vara's Favor and Temple Scribe which are really good cards as well as Bolster which can blow opponents out. This deck runs Lumen and Slug as a bit more midrangey finishers.
As for Sideboard, SST is to deal with fliers. 3 suffocates to deal with any deck running Groundbreaker. 3 Deathstrike for decks that run few annihilate targets. 2 more Banish to deal with armory or chalice. Steward is then for reanimator.