[Jochemd]

pawn Код:

public OnPlayerCommandText(playerid, cmdtext[])
{
    if(!strcmp("/kill",cmdtext,true))
    {
        SetPlayerHealth(playerid, -10);
        return 1;
    }
    if(!strcmp("/heal", cmdtext, true))
    {
        if(!IsPlayerAdmin(playerid)) return 0;
        {
            SetPlayerHealth(playerid, 100);
            return 1;
        }
    }
    return 0;
}

It's not that hard

Remember: To kill a player, always set health lower than 0, because it would just stand there with no health left, unable to do anything.