Hello moparscapers, I have had some trouble with this myself, I finally got it and I wanted to share this with the others out there.
Please don't hate. I know there are quite a few tutorials out there about this, but, i've found this to be much easier.
So, without further adieu....
You're gonna want to open up your " Source/Base" Folder.
THen, you're going to want to look for: " NPCDrops.TSM " This should be located in; Source\Data\cfg - Inside CFG Folder.
Open the file up, you can use a notepad, text document, or notepad++ my favorite.
You should see a bunch of digit codes like this;
Now here's how you create your own;
8133:404113:14111:1452:202362:351995:500000384:701754:1001514:75890:7509144:250##NOTE* first line is Normal drops line.
8133 = THE NPC ID
40 = Percent of rare drops.
4113 Is the ITEM ID and 1 Is the amount.
The second line is the rare drops line.
I hope this helps#@!