Damage increases every time a player receives damage.
The damage increase can be tweaked and separated between different damage types using the Asset Editor. The damage increase can be configured to be global (default) or per player.
/hardcore set [amount] - Set the current multiplier to the specified amount
/hardcore reset - Reset the multiplier
/hardcore inspect - Inspect the multiplier of the world
/hardcore inspect --player=[username] - Inspect the multiplier of a friend