That dropModification method doesn't look like it makes any sense at all. How can your mod increase a drop rate when your donator mod is under 1 and your sponsor donator is over 1? If the higher the mod the better the drop rate, then your regular donators will have a worse drop rate than normal players. If the lower the number then the better the drop rate, then your sponsor donators are getting screwed because a regular donator has a better chance
Secondly this picture you posted has nothing to do with your "drop rate" as you call it. In NPCDrops.java you have a enum called DropChance that says what each of your rates are. For example, your ALMOST_ALWAYS drop rate should have a 1/2 chance however your ALWAYS drop rate should drop every single time
Third, drops.json handles all of your actual drops so if you want something to drop every single time then in drops.json you set its chance to 0 since thats the ALWAYS drop rate that we just found out was in NPCDrops
