[CalvinC]

Use SetPlayerHealth to set a player's health, if you wan't to apply damage, use GetPlayerHealth.

pawn Код:

new Float:health; // Creates a float called "health"
GetPlayerHealth(playerid, health); // Stores the player's health in the float "health"
SetPlayerHealth(playerid, health - 90); // Sets the player's health to the float "health" - 90

There are several callbacks where you can detect if the player damages another player, like OnPlayerTakeDamage and OnPlayerGiveDamage.