The unblockable indicators are unlocked after a few encounters with the boss, but maybe I should make it be less encounters. At first being surprised and not knowing what defense is safe to use is the intended experience. Guidebook I'll work on for sure, that's my top priority now to explain the game better to the player.
The only drill power halved by perils is the Shieldrill, though (I was going to have a DP halving one, but didn't like the balance of it and removed it). The 40k boss, which I'm thinking is the one that doesn't show you her face, buffs your DP during the battle with her, then is supposed to debuff you for all she increased, but maybe, just like the shield switch, I didn't make her debuff reset between runs. I'll check the code to make sure (ToT)
Didn't consider death at the perils and forgot to put a death check there, oops.
You're a great debugger, thank you for reporting all those things!