Do I score a point playing Baron Nashor?

Yes, playing Baron Nashor can score you a point, provided you have not already scored the Baron Pit battlefield during that turn.

According to RiftJudge FAQs #9221 and #9698, this works because:

1. Creating and Entering: When you play Baron Nashor, his ability adds the Baron Pit battlefield token to the board if it is not already present, and he enters that battlefield.
2. Conquering: Playing a unit directly to an empty battlefield (which the Baron Pit is upon creation) counts as "conquering" that battlefield.
3. Scoring: Per Rule 463, a player scores through a "Conquer" when they gain control of a battlefield they have not yet scored this turn. Since you are gaining control of the newly created Baron Pit, you satisfy the requirements to score a point.

Important Nuances:

• Once Per Turn: Per Rule 447, you may only score from a specific battlefield once per turn. If you have already scored the Baron Pit this turn, playing Baron Nashor there will not grant you another point.
• Final Point: If you are attempting to score your final point (the point that reaches your Victory Score) by conquering, you must have scored all battlefields currently in play during that same turn to win the game. In a 1v1 game, playing Baron Nashor creates a 3rd battlefield, meaning you would need to have scored the two original battlefields plus the new Baron Pit in the same turn to win (RiftJudge FAQ #10037). If you conquer the Baron Pit but have not scored the other battlefields, you will draw a card instead of scoring a point (Rule 466.1.b.2).