Preview because a certain guidlmate thinks I'm not making any sense. I agree. Just look here and you'll understand what it is.

Hay guys and gals, it's me the Google Docs lover! Straight to the point, I made an Excel document (*.xlsx) to keep track of how many Black Kats I need to kill and whatnot. All you need to do is specify which gear to get (NOTE: if you're going for, say, only the 5* version of something, don't check the 3* or 4* versions), if you've done today's prestige mission and lastly, how many pages you have acquired, including the ones you have used. All but the last of these have drop-down menus for the options. Don't enter data where it shouldn't be. Don't change the formulae. Don't lick Chromas.

What? You want th- here it is.

To use this in Google Docs, make a new spreadsheet, press File > Import and the rest should be pretty self-explaining. Use the file found above.

Edit: I realise I might've been a tad unclear. This is not about keeping track of how many Black Kats you've killed, rather how many you need to kill based on how many Ancient Pages you have. It is not about the Book of Dark Rituals or Black Kat Cowl, only about Ancient Pages and potato sacks, masks and cowls. I apologise for that.
Oh yeah, GMs might or might not want to move this to The Arsenal. I'm not sure which is the most appropriate so I'm leaving that to you.