#define DURATION 0.5 // длительность

new g_iFlashDuration = -1;

public OnPluginStart()
{
  g_iFlashDuration = FindSendPropOffs("CCSPlayer", "m_flFlashDuration");
  HookEvent("player_blind", OnPlayerBlind);
}

public OnPlayerBlind(Handle:event, const String:name[], bool:dontBroadcast)
{
  new client = GetClientOfUserId(GetEventInt(event,"userid"));
  SetEntDataFloat(client, g_iFlashDuration, DURATION);
}