More Detailed Description At This Link
What is HeartCore?
HeartCore is a multiplayer-friendly semi-hardcore datapack designed to provide a fair experience between Hard and Hardcore difficulties. In HeartCore, each player has three lives, and lose 4 hearts with each life lost. However, by crafting an advanced golden apple referred to as a 'HeartCore', a player can regain a lost life. For recipes of each of the stages of a HeartCore, any player can use the /trigger info command in game. Players are set into spectator upon their third, and final, death.
To reset someone's lives, an operator can use the command: /scoreboard players set [username] hardcore_deaths -1
For item recipes in the pack, visit this link:
https://hollikill.net/html/HeartCore.html
INSTALLATION INSTRUCTIONS
place a copy of HeartCore_datapack.zip into the datapacks folder in your world, and place a copy of HeartCore_textures.zip in your resource packs folder and enable it.
If you are using this on a server, make sure the resource-pack line in server.properties looks like this:
resource-pack=https://hollikill.net/misc/HeartCore_textures.zip
Additionally on servers, make sure HeartCore_datapack.zip is enabled by going in game on your server and typing /datapack enable "HeartCore_datapack.zip"