QCF Design Community

Sorry if this is just me being a bit obtuse, but I am attempting the second puzzle in the 'Hello, halflings!' puzzle pack. So far I have tried doing it on my own and following every solution guide I could find to finish it without luck. The sign in the dungeon, as well as many guides, mention using the death protection, but though I have it it does not activate in any way and despite my best efforts I cannot defeat the final monster.

I have looked at Youtube and the solutions posted on this very forum, but even going slow and following the step by step directions of others I still seem to die. Is this a bug with the protection buff, a change in the game since solutions were posted, or am I just that stupid?