Hi, I was wondering how I can make a hombrew feat that gives a spell, use a pact spell slot? So, in our campaign, my patron granted me an additional Eldritch Invocation, which I chose Mire the Mind so I can cast the Slow spell. I was able to make a homebrew feat that gave the Slow spell with the correct save dc and 1 use. However, it's supposed to use a pact spell slot, which I cannot seem to get it to do that. I was able to make it a 4th level spell (the same for all my pact spells) and only one use per long rest, but I can't seem to get it to use one of my pact spell slots. I mean, it's not a big deal since I can manually do it, but I have a tendency to forget things like that.

You will have to list it in the text as a reminder to yourself to check off that box. We cannot make a feature that automatically uses spell slots like that.