OP Diamond Items by WetNoodle
This mod, just like the title suggests, adds OP items to the game. These items include armor, tools and weapons.
The Gauss Gun Mod by TheUltimateHose
A mod that adds a Gauss gun to your Minecraft. I recommend having something like Thermal Foundation installed because you will need a RF-source, copper ingots and tin nuggets
SuperSlopes - IntCorners by MetaDark, Kaevator, Malivil
SuperSlopes is a mod that adds multiple new building blocks into the game so players can create more complex structures. Interior Corners is a subcategory under SuperSlopes which adds multiple new interior corner blocks.