Arcadian Octo Duck

This mod, named by GitHub's suggested name feature, raises the stakes of boss fights by putting your precious hearts at stake. Get killed by a boss, lose a heart, simple as that. Beat a boss to regain your lost hearts.

The mod can be configure to deplete hearts one at a time, or remove 5% or 10% when you die, black or whitelist entities, or disable regaining of hearts all together.

For mod authors, if you don't want your boss to make a player lose a heart, simply send the boss class as a String IMC message with the key boss_black_list.

Example:

FMLInterModComms.sendMessage("aod", "boss_black_list", EntityWither.class.getName());

If you want your mob to make players lose a heart, simply use the key boss_white_list instead.