So, I have been thinking of ways for me to streamline access to enemies that I can toss at my players. I normally plan in advance what they will fight but I want to be able to switch up what they fight based on their actions.

My first thought was to throw all the enemies onto index cards and then organising them by type and faction.

so like Chaos/Daemon/Nurgle, etc.

I want to know what you guys do to achieve similar if you do anything. Also any insight on the perfect index card size? I am going to start working on a template that I can just plug stats into and print. If I get something good I will post a link.

If you're talking about long-term; every time a stat a bad guy of a type that I might reuse, I copy-paste it to a document (organized, as you suggested, by faction or whatever is appropriate). Then if I ever want to use that same bad guy again, I just copy-paste back to my running outline.

If you're talking about short-term; the variety of enemies that my PC's are likely to encounter during a giving session is usually small enough to fit on a single page. If my players go way off the page and I have to improvise an encounter, I'll just wing it on the stats.

At any rate, the index cards sound like a good idea; but I have one bit of advice: find a format that works well for you and then stick with it. I find that if I'm inconsistent with my stat formatting, it can make finding a needed number a little frustrating.

A printable PDF of these would be great, so we could just cut them out of A4 sheets and stick em on a roladex lol