<Custom Synthesis Effect>
var bottle = $dataItems[123];
$gameParty.gainItem(bottle, 2);
</Custom Synthesis Effect>
For this notetag, the 'item' variable will refer to the item being
synthesized. Changing it will do nothing but it will be used as a
convenience variable to refer to it.
<Custom Synthesis Effect>
var Vitamin X = $dataItems[76];
$gameParty.gainItem(Vitamin X, 3);
</Custom Synthesis Effect>