I think this is what you are looking for. It's what I use for my Jedi Knight plugin.
PHP Code:
public Action:OnTakeDamage(victim, &attacker, &inflictor, &Float:damage, &damagetype, &weapon, Float:damageForce[3], Float:damagePosition[3], damagecustom)
{
if( !IsValidClient(victim) || !IsValidClient(attacker) || !g_bIsJedi[attacker] || g_bIsJedi[attacker] == g_bIsJedi[victim] )
return Plugin_Continue;
if(g_bIsJedi[attacker] && damagetype == 8)
{
damage = damage * 15;
}
if(g_bIsJedi[attacker] && damagetype == 64 )
{
damage = damage * 15;
}
//next line is for debugging
// PrintToChat(attacker, "Weapon: %d, Damage type: %d",weapon, damagetype);
return Plugin_Changed;
}
When posting code it is helpful to click on 'advanced' button and click on php icon to wrap your code in the correct format.