The Synergizer is a socializing tool in the Captain Outfitter. It allows Holo Charm, which is an upgradeable, energy using version of charm.
The Synergizer enables the Holo Charm ability, which can be upgraded but uses energy. It is effective at socializing large creatures difficult to ally.
Holo Charm uses up energy, unlike the Regal Ring's Royal Charm, and thus, can be upgraded. If it is going to be used to impress creatures extremely tough to impress, then Synergizer is worth it. Otherwise, Regal Ring is better as it uses less energy, thus making it good for captains who have a shortage of energy.