Adding these in their own post so I can direct-link in my sig:

Sindale: Safety tools
The fun of monsterhearts exists in fraught, messy, and dangerous subjects. We're exploring characters that are messy and imperfect and make bad decisions and get themselves and other people in trouble. That means we're almost certainly going to encounter scenes or topics that might make us uncomfortable. Some level of discomfort is good, and even exciting. This is, after all, a horror game. But for times where any of us is experiencing bad discomfort, we'll be using safety tools to address the situation.

In this game, we'll be using X-cards and Fades-to-black. X-card is a way to cancel content you're not okay with having in the game. For example, if I describe my Witch character as doing magic by commanding swarms of wasp-like faeries, and you've got a phobia about bees, you can invoke the X-card, and we'd change the fiction so wasps aren't a part of the story.

Were we playing around an actual table, the X-card would be a physical card that we could touch or hold up, though that's obviously not the case for us because internet. So if you need to invoke the X card, just post "X-Card" in the thread, or alternately, PM "X-Card" to the MC. It might help to include a little explanation of the content you're uncomfortable with (e.g. "No bees, please"), but it's not necessary--and in practice when someone invokes the X card it's usually pretty clear why they're doing so.

Fading to black, by contrast, isn't about making sure things don't happen in the game--it's just about making sure that the thing happens "off-screen". So if the Mortal and the Ghost are making out in the men's room behind the bleachers and it's clear they're going to progress to further amorous activities, we can fade to black rather than describe the events in detail. The faded events still happen in the context of the game's fiction (and in this example, the sex moves will trigger), but they aren't described in the context of the conversation between the players and the MC.