"Birds of the World" and "The end is nigh!" do nothing if them read within moonstorm and in caves, respectively.

5 minutes ago, Stormcloud Gray said:

Would be cool to have one more option for forcing earthquakes apart from explosives.

Lux aeterna does, apparently.

8 hours ago, Stormcloud Gray said:

Rather than just failing for real in the caves as the fix maybe "The End is Nigh!" could summon an earthquake instead?

 If the book is considered as a strong magical object, which it is supposed to be how idea, a shadow manipulator is needed to create it, then it, like a purple staff, can also summon a small earthquake.
 But if we consider the book as an object that simply summons armageddon from lightning, then I doubt that they are able to somehow pierce the Earth's crust and get you

I don't mind if the book has an alternative effect in caves, as a punishment for using a strong magical object in the wrong place, for example, if you read it in a dangerous place, then its effect will be more deadly in order to better match its name and possibly give the book a second life, reading in ruins - you get a nightmarish cycle, like example.
But this item can be easily improved if there are more items/mobs or events in the game that are really positively affected by lightning and then the effect in the caves will be slightly inappropriate.

 

Changed Status to Fixed