This mod basically gives you back the behaviour of the old Iguana Tinker Tweaks for MC 1.7.10 (and downwards). It is based on Tinker's Tool Leveling, but has a completely different behaviour: For every new level, you get a random modifier applied to your tool. If you want to go fully crazy, you can configure the mod to give you a free modifier every level on top of that.
This mod is currently only available for MC 1.12. You can find the latest release on GitHub: https://github.com/liketechnik/Liketechnik-s-Tinker-Tweaks/releases
To use this mod you obviously need Tinker's Construct.
Please use the GitHub Issue Tracker for reporting problems and crashes or making feature requests.
This mod forked from Tinker's Tool Leveling, that provided the base for this mod. I'm really thankfull for their mod (you can find the reason for the fork here: SlimeKnights/TinkersToolLeveling#8), if you just want the free modifiers, go there.
The idea comes from Iguana Tinker Tweaks, that added the bahaviour in MC 1.7.10.
Liketechnik's Tinker Tweaks is licensed under the MIT License, the same license as the project it originates from.