[wrecked_]

#include <amxmodx>
#include <hamsandwich>

const DMG_NADE = (1<<24)

public plugin_init()
{
    register_plugin( "No Self-Nade + Damage", "1.1", "Wrecked" )
    
    RegisterHam( Ham_TakeDamage, "player", "HamTakeDamagePre", 0 )
}

public HamTakeDamagePre( vic, inf, att, Float:dmg, dmgbits )
{
    if( dmgbits & DMG_NADE )
    {
        if( vic == att )
            return HAM_SUPERCEDE;
            
        new Float:newdmg = dmg * 2 // use this variable to change the dmg
        
        SetHamParamFloat( 4, newdmg )
    }
    
    return HAM_IGNORED;
}