This is an addon to Apotheosis, also a core mod.
Apothieosis didn't overwrite these methods:
net.minecraft.world.item.enchantment.EnchantmentHelper.getEnchantmentCost()
When you call this method in vanilla ways, it will return the default Enchantment Cost instead of the cost modified by Apotheosis.
net.minecraftforge.common.extensions.IForgeBlockState.getEnchantPowerBonus()
When you call this method in vanilla ways, it will return the default Enchant Power Bonus instead of the Eterna of Apotheosis.
net.minecraft.world.item.enchantment.Enchantment.getMaxLevel()
net.minecraft.world.item.enchantment.Enchantment.isDiscoverable()
net.minecraft.world.item.enchantment.Enchantment.isTradeable()
net.minecraft.world.item.enchantment.Enchantment.isTreasureOnly()
When you call these methods, it will return defaulted properties of the enchantment.
This mod used mixin and asm to fix them.
When you applied this mod, these methods will be redirected to Apotheosis ways.