[Lordzy]

You must use SetTimerEx to use 'playerid' in the timer.

pawn Код:

public OnPlayerSpawn(playerid)
{
 SetTimerEx("LH", 10000, true, "d", playerid);
 return 1;
}

forward LH(playerid);
public LH(playerid)
{
 new Float:hp[MAX_PLAYERS];
 GetPlayerHealth(playerid, hp[playerid]);
 SetPlayerHealth(playerid, hp[playerid]-1);
 return 1;
}

2: I think you must use symbol " ' ".