This mod anvils which function similar to the vanilla anvil but better.
First, the damage from anvils is now uncapped so mob farming with them becomes practical.
Second, if an anvil falls on a mob, it negates all damage that would've happened to the anvil if it hit the ground.
The Gold Anvil has 4x level cap and 4x break resistance.
The Diamond Anvil has an unlimited level cap (32768 in 1.12) and 64x (32x in 1.12) break resistance.
The Stone Anvil has 1/2 level cap, and breaks after only 3 uses, but is cheap.
In addition this mod has support for over a dozen different mods with up to 24 additional anvils that have varying stats which can be seen as a tooltip.
And if that isn't enough, custom anvils can be made using the built in config.
Notes for 1.14.x:
Due to the texture changes, all modded metal anvils are on hold until someone provides textures for them, they still have functional stats though and can be manually enabled if desired with datapacks and resource packs/ or resource loader.
For indepth questions and other stuff: https://discord.gg/vZxnfa4