If I have a 2 might unit attacking into an empty battlefield, opponent plays orange Rengar, I stun the orange Rengar with Back Off, how will the combat resolve and if Rengar will score a point?

Sequence of Events

1. Your Move: You perform a Standard Move with your 2-Might unit to an open battlefield. This initiates a non-combat showdown. You are the Attacker (Rule 442.1.a.1).
2. Opponent's Response: Your opponent plays Rengar, Trophy Hunter as a [Reaction]. Because there is an enemy unit present, they may play Rengar to that battlefield. Upon playing Rengar, your opponent becomes the Defender (Rule 442.1.a.2).
3. Your Response: In response to Rengar entering play, you play Back Off as a [Reaction], targeting Rengar. Rengar becomes Stunned.
4. Showdown Conclusion: The chain empties, and both players pass focus. Since units from both players are present, the non-combat showdown transitions into a combat showdown.

Combat Resolution

• Combat Damage Step: Your 2-Might unit deals its Might in damage to Rengar. According to Rule 423.1.b, "A Stunned Unit does not contribute its might to damage in the combat damage step." Therefore, Rengar does not deal damage to your unit.
• Combat Cleanup:
  • Units heal (Rule 461.1.a.1).
  • Attacking units are recalled to their controller's base if Defenders are still present (Rule 461.1.a.2).

Will Rengar Score a Point?

Rengar may score a point if he survives the combat.

Points from Conquering (Rule 464.1) are established by taking control of a battlefield. Control is established during the resolution step (Rule 461.5) if a player has units remaining and the opponent does not:

• If Rengar survives the combat damage, your 2-Might unit is recalled to your base per Rule 461.1.a.2.
• If Rengar remains on the field as the only unit remaining, your opponent will establish control of the battlefield and potentially score a point.
• If your unit successfully defeats Rengar, you remain at the battlefield, allowing you to establish control and potentially score a point.

Note: I could not fully verify this ruling against the retrieved rules.