Pushing the King to d5 also works, but my original idea- just like your line of thinking, was "return to the square it just left" like in my checkmate example in the Pieces section. Even though it can do a lot, I'm pretty sure the sentry is still just a bit weaker than a bishop (and that's how I wanted it), for example if the sentry were a pinned piece here, it can't perform the final mate move, while a bishop already has it mated. Advantages and disadvantages is what I was going for.
Nice one Ben, exactly right. In addition:
Pushing the King to d5 also works, but my original idea- just like your line of thinking, was "return to the square it just left" like in my checkmate example in the Pieces section. Even though it can do a lot, I'm pretty sure the sentry is still just a bit weaker than a bishop (and that's how I wanted it), for example if the sentry were a pinned piece here, it can't perform the final mate move, while a bishop already has it mated. Advantages and disadvantages is what I was going for.