If you are working in an IDE I can help, but if you are in MCreator I cannot help. I do not EVER recommend using MCreator. It is always better to actually learn the concept instead of downloading a program that does it for you. It will also give you a new skill if you learn actual modding. Then, you'll be able to code in Java. If you do decide to use an IDE, reply to this comment and I will help you. I do not think MCreator can even make potions, so sorry.
ATTENTION: All my mods are in Fabric and use the Fabric Mod Loader and the Fabric API. I do not make mods in Forge, because I deeply dislike Forge. Sorry!
One more thing: I know I'm not IMPORTANT ENOUGH to be asked things like "can you make this mod for me?" but still. I check the mod requests section on the MC Forums at least once a week. If you have anything you want me to make, post it there and there is 99.99% chance I will see it. And if it's good, I will make it and post it on the same thread. I know no once cares but still. Just so you know, you feel me?
You should ask on the Mcreator Forum... and update to the new 2020.5 prerelease. and there is nothing wrong with using Mcreator to make mods, and you can use it to code manually, if you choose to and want to go further and learn the coding..