[Hobod]

Set a timer for 1 second that repeats.
Then in the function decrease the players health.

pawn Код:

// Your function
forward Death(playerid);
public Death(playerid)
{
       new Float:Health;
       GetPlayerHealth(playerid, Health);
       SetPlayerHealth(playerid, Health-5);
}

i'm not the with timers but i hope this helps!