Best scripting mod to ever exist for any version

Absolutely phenomenal mod for modpack developers. For complex packs it is very important that you can program stuff in a sane way, allow code reuse etc. and Groovyscript supports that much better than every other scripting mod, while not making learning the baseline hard. Having builtin support for every major mod is icing on the cake. I also had good amount of fun contributing more support stuff. The only issue is that sometimes old stuff is incompatible because the mod periodically breaks its public API, but even then the lead dev often would go out of his way to contribute an update to another mod updating its API if possible