To elaborate, the percentage of 'Default protection percentage' works backwards.

1% protection doesn't actually mean it has 1% more protection, it actually means the structures only take 1% of the damage. Vice versa, 80% means it only takes 80% of the damage.

So if you wanted structures to take 20% less damage, you'd have to set this option to 80. Which wasn't at all clear (And I don't think intended).

You are completely right, I'm embarrased I missed that. Thats what I get for only testing 50% and 100% (which is hardcoded to not deal damage).

In any case, 1.0.5 fixes this. Thank you for bringing it up.