Hi @xzxixin,
Thank you for your report.
We are unsure if this is a bug. You are correct that the effect “Deal 4 damage/Remove 3 threat from a scheme” is written in the cost part and should be resolved even if your hero is stunned or confused. However, the effect part modifies the value of the cost part. As a result, we implemented the effect “Deal 4 damage/Remove 3 threat from a scheme” in the effect part, which is necessary due to the “additional” keyword.
If this is indeed a bug, rewriting the cost system would require significant work on our end.
Thank you for your understanding. If you have any further ideas or suggestions, please feel free to share!