Re: How to shorten the game?
After several test plays I have come to conclusion that in fact you only need 3 Monsters at all. And here is the variant:
The Small Book of Madness
1) when preparing the Grimoire / Book of Madness, add only 3 monster sheets (1 starting + 2 in the middle + the final page)
2) new page may be turned over only if all curses have been broken (i.e. via success condition)
3) if there is at least one curse remaining at Invocation (1), remove all of them and the actual Monster reappears (i.e. remains undefeated): add new curses + execute Monster's arrival effect
4) if the 3rd / final Monster is not revealed at the start of round 6, all players will automatically lose (in addition to the Madness or final page loss condition)
5) for experienced players: add 1 or 2 Madness cards to each player's deck at the setup
In this way, the game should become quite quick, less repetitive and with stronger feel of battle/progress. In addition, it should remain similarly challenging.