And of course Spectre Butt's stage video is ready just as I post before. And the first thing that happens in Lich Yard is pretty much why I don't use the sentry fuse - there's a fair amount of trying to go down narrow tunnels in the game. It works better for Butt Butt, who can simply downstab, but the other Butts have to improvise. The good news is that a burst can break dirt blocks you're standing on.
Yeah, coins embedded in walls is just an indicator of "hey here's a new side section for Plague Butt," and the side paths loop back to the main path.
If you don't get the stage relic beforehand, you can still get the Arcana - you just have to pay for it.
The one dark screen with the cipher frog and music paper is really fun to try and chain burst through. You
can burst your way up past the dark room with the spike floor death zone but NOT with the float burst (or if you can you need to be super precise with it). Arcana is like Stamina from the newer Zelda games - if you drain it dry it has to fully refill before you can Arcana again.
Spectre Butt is a really good boss to showcase the Lob Casing with. Sentry Fuse is probably a good fuse to use against this guy, now that I think about it.
@SAJewers:
What about with the Panda Cloak, where you can't control what you have to use? I love using that thing.