Sit across from each other. Put the three Site cards in a row: LEFT, MIDDLE, RIGHT. Set both Slava sliders to 0. Put your Warden face-up in front of you. Keep your teaching deck in the order it came in (do not shuffle yet).
Every turn you both do the same thing together: gain Embers, place cards face-down at Sites, flip together, score. That is the whole game.
Draw the top card. You each have your Opening Spirit (the gold pip): Hearth = Domovoi Hearth-Ward (Power 2), Deep = Karzelek Mine-Sprite (Power 2).
Both place your Opening Spirit face-down at the MIDDLE Site. Flip together.
Power 2 vs Power 2 is a tie. Nobody has strictly more, so nobody wins the Middle and nobody scores. Slava 0 to 0.
Draw one card. Deep has Rusalka Drowned-Maiden (Power 3, Omen: Clash 3). Hearth has Kikimora Spindle (Power 1, Omen: draw a card).
Deep places Rusalka at the MIDDLE. Hearth places Kikimora at the LEFT. Flip together.
MIDDLE: Rusalka's Clash 3 sends one enemy Spirit here with Power 3 or less to Nav, it sends Domovoi (Power 2). Domovoi does not die: it crosses to your Nav, face-up, and waits. Deep now holds the Middle (Power 5 to 0), Deep +1.
LEFT: Kikimora is alone, so Hearth +1, and draws a card. Slava 1 to 1.
Hearth: Reborn Domovoi from your Nav (pay 1) and place it at the LEFT, beside Kikimora. Deep: play your next Spirit at the RIGHT. Flip together.
Domovoi comes back through its Reborn: +1 Power, forever (now Power 3). Its Vigil gives your other Spirits here +1, so Kikimora becomes Power 2. Your Left is Power 5 and uncontested, Hearth holds it again. Deep takes the Right.
That is the entire game. You already know how to play.