This is a MinecraftForge mod which recreates the previous incarnation of the proc (Powerful Rampage of Course!) from Robert "Urealms" Moran's Minecraft Game called Dwarves vs Zombies. A proc occurs when you kill a entity with a sword named "Dwarven Runeblade" (Without the quotes), This will give you the proc buff which will allow you to 1 hit any other entities for 3 seconds. If you manage to kill another entity within those 3 seconds, The proc is refreshed and you can continue killing your killing spree.
When monsters proc
You can put this in any modpacks you want without needing permission.