On the Temple Sacrifice I have noticed a bug. When you knock down this piece:
and then hit the indestructible block here:
Only the electricity barrel explodes but not the TNT. Some blocks just fall on it with no result.
However. Hitting it in the same exact place (the trebuchet only have a range of shots it can hit, some being the same) without the metal connector down results in TNT and electricity barrel explosions. I'm not the only one with this problem of course.
So yeah, this level is not immediately obvious, and that's partly my fault. Sorry.
What you have to do is fire down below and get the electric barrel to charge the platform above it. This should take out the guys below in a chain reaction. Then quickly throw to knock over the column at the top down on top of it, while the platform is still charged. Hopefully, if you get it quickly enough, you'll connect the two platforms and electrocute the knights as well. But you have to be kind of quick with it.