It doesn't open when I click "Play" it instantly says "Java Runtime Configuration" Error. I know its the mod because it works when I remove the mod.

Please post a crash report.

having the same issue.

using only Optifine (3 mods)

crashes even without optifine

https://pastebin.com/sJQdid4x

@Dechetmew you need to add ForgeRocks and Mixin, as described in the README

@InternalMegaT can you send either a crash report or a log, otherwise i can't tell what the problem is

@Dechetmew you need to add ForgeRocks and Mixin, as described in the README

ok thanks