If I have an Ivern Brush on top of Aspirant's Climb and score to 8 points by holding and my opponent also already has 8 points - if I decide to get rid of the brush - who wins?

To determine who wins when you score at a battlefield occupied by a Brush token that replaced Aspirant's Climb, we must look at the sequence of the "swap back" mechanic and how Aspirant's Climb interacts with the win condition.

The Sequence

1. Scoring and Trigger: You hold the battlefield, reaching 8 points, and trigger the Brush token’s ability: "When you score here, you may replace this with the battlefield it replaced."
2. Swapping Back: You choose to "swap back." Per Rule 438.7.b, the Brush token ceases to exist and Aspirant's Climb is returned to the battlefield.
3. Passive Re-activation: Per FAQ #7987, Aspirant's Climb has a passive effect that is active simply by being in play: "Increase the points needed to win the game by 1." Once Aspirant's Climb returns to the battlefield, this passive effect immediately applies, raising the Victory Score from 8 back to 9.
4. Victory Check: According to Rule 467, a player wins if, during a cleanup, they have points greater than or equal to the Victory Score AND more points than any opponent.

The Result: The Game Continues

In your scenario, both you and your opponent are at 8 points.

• Victory Threshold: Because Aspirant's Climb has returned to the board, the Victory Score is currently 9.
• Tie: Since both players have 8 points, neither player has reached the required 9 points, nor does either player have more points than the other.

Conclusion: Neither player wins. Because the win condition (reaching 9 points and having more points than the opponent) is not met during the cleanup, the game continues. You have successfully restored the battlefield, but the Aspirant's Climb has simultaneously pushed the victory threshold out of reach for both players, forcing the game to proceed until a player can gain an additional point to break the tie.

This interpretation is based on the interaction between passive battlefield effects and victory conditions as defined in Rule 467 and the clarification in FAQ #9987.