Lifesteal

Lifesteal awards a permanent extra heart each time a player kills a hostile mob. Max health grows by two health points per heart and is refilled when earned.

What it does:

• Runs on both client and server for Minecraft 1.21.x; compatible with 1.21 servers.
• Grants hearts only for hostile (monster spawn group) mob kills; players and neutrals do not count.
• Reapplies saved hearts on login and after respawn so progress persists through death and server restarts.
• Stores per-player heart counts in world persistent data keyed to each player's UUID.
• Clamps current health to the recalculated maximum to avoid exceeding the new cap.

Notes and considerations:

• All hostile kills give the same reward and there is no built-in cap.
• Progress is saved per world and per UUID; swapping worlds or IDs will not carry hearts over.

Server Validation

✅ Server validation passed - The mod was tested on a real Minecraft server and loaded successfully.