Yanfly Engine Plugins is a plugin library made for RPG Maker MV, a wonderful piece of software to help you make that role playing game of your dreams. You can find out more about RPG Maker MV here.
Here’s a neat little trick you can do with the Skill Core plugin: recreate the Molten Giant card from Hearthstone. Its effect is that the card costs less mana depending on how much health the hero is missing. Let’s do that, too, in RPG Maker MV using the Skill Core plugin!