Rek'Sai

Void Rush provides a top-two play without needing a conquest first, reduces the chosen card's Energy cost by two, and draws the cards you did not banish. Undertitan is the payoff that connects those reveals to the board: revealing it from the deck adds two Energy immediately, and playing it gives your other units +2 Might for the turn. Build the small units first so that second effect changes more than one fight.

• Early gameLook for Dredger, Broker, or Emissary with a follow-up that produces a useful board. A cheap first card makes Hopeful cost two Energy instead of four. Manufactor adds a Recruit here when played; Captain needs Legion for its two Recruits. Put them at base if they need to attack later, or at a battlefield you already control when you need immediate defenders. Breacher costs three Energy normally, or four and one Fury Power to enter ready. Do not spend the Emissary Empower cost automatically. One Energy and one Order Power is worth paying when its eventual death will leave a useful pair of bodies, but not when that payment prevents the attack or answer you need now.
• MidgameUse Cull when the opponent has a unit worth losing and you can offer Dredger, Broker, an empowered Emissary, or a spare Recruit. The opponent chooses their own casualty, so it is much less impressive when they have expendable tokens too. Cleave gives Assault 3 for one Energy. Blood Rush gives Assault 2 and can repeat for another Energy, either concentrating four extra attacking Might or splitting the boosts. Neither is a defensive Might bonus. Keep ordinary resources for the reveal after the conquest. If the board cannot earn that conquest, Void Rush can supply a play or simply draw both revealed cards instead of forcing a bad attack.
• Late gameDevelop the bodies you want Undertitan to improve before its play trigger resolves, then decide which two fields the turn can actually contest. Inferna can join a battlefield where you already have a unit as a Reaction, and Vi can do the same; Vi's stun comes when she attacks, not merely whenever she is played. Falling Star can deal six to one unit or three to each of two, including units at base, but needs two Fury Power and normal Main-Phase timing. Rage Amplifier gives your whole board +1 Might, or +2 instead after its expensive Empower. Pay for that upgrade only when it changes the remaining points. Another useful unit, a reveal, or keeping an answer available may do more than spending six Energy and one Fury Power on the extra Might.