Diamond Dust and Diamond Berg

Diamond Dust (ダイヤモンドダスト, Diamond Dust) and Diamond Berg (ダイヤモンドバーグ, Diamond Berg) are related Mercury Psynergies featured throughout the Golden Sun series that are functionally identical but have different levels of power. They are among the strongest offensive Psynergies in the series and, up through Golden Sun: Dark Dawn, are only available to Mercury Adepts.

Basic description
Diamond Dust and Diamond Berg are offensive, single-target Psynergies that are Attack-dependent, meaning characters with higher Attack ratings will deal more damage with these attacks. In addition, the caster's Mercury Power and the target's Defense and Mercury Resistance all factor into the damage dealt.

Visually, Diamond Dust resembles a series of large chunks of ice flying in from an angle to hit an opponent. In Golden Sun: The Lost Age, the ice chunks fly in at the same time, while in Golden Sun: Dark Dawn, the chunks hit consecutively.

Diamond Berg maintains Diamond Dust's ice theme, but differs slightly in appearance. In The Lost Age, a large block of ice falls from the sky to encase an opponent. The caster then strikes the ice chunk multiple times to break down the ice. In Dark Dawn, cold energy focuses in on the target. The caster will then attack the ice chunk, which varies depending on the weapon. If a sword or staff is used, the caster will physically strike the target as in The Lost Age; if a bow is the equipped weapon, the caster will fire arrows in rapid succession to chip off ice. In both cases, the ice will then explode in a final burst.

Availability
Diamond Dust and Diamond Berg are unique to the Mariner class series and the Aqua Squire class series, meaning only Piers and Amiti can cast them, and only if they have no Djinn except Mercury Djinn set.

Both Diamond Dust and Diamond Berg are learned at level 12. However, only Diamond Dust is available at first: Many Psynergies are only available to the more advanced versions of a class, and Diamond Berg is no exception. What separates Diamond Dust and Diamond Berg from most Psynergies is that Diamond Berg replaces Diamond Dust. To access Diamond Berg, the appropriate Adept must have at least six Mercury Djinn set, changing him to either the Captain  or Admiral class, in Piers's case or the Aqua Lord or Aqua Master class in Amiti's case.

Analysis
General: Diamond Dust's damage output is roughly the same as other elemental physical attack Psynergies like Heat Wave and Ragnarok, but in practice Diamond Dust appears to deal slightly less damage due to the lower Attack multipliers of the Mariner and Aqua Squire classes. Diamond Dust is roughly on-par with a mid-game Unleash (with the main difference of costing Psynergy Points instead of activating at random) and is more valuable the earlier it is acquired. Even in the middle and late stages of a game, Diamond Dust may be preferred over Unleashes due to its reliability. Diamond Berg, by comparison, may not be as practical as Diamond Dust: Despite the increased damage output, Diamond Berg's high PP cost greatly reduces the number of times it can be cast, especially considering the classes' low PP pools.

Vs. Djinn: Many, though not all, offensive Djinn use a damage multiplier instead of a fixed damage increase, in addition to the Power - Resistance multiplier. As a result, these Djinn have the potential to be much stronger than Diamond Dust and Diamond Berg, especially in the later stages of a game when the Adept in question has a higher Attack rating. However, unleashing Djinn in battle places them in Standby, resulting in two main disadvantages. First, Djinn must be Set to affect a character's class; unleashing a Djinni may result in lower statistics across the board, including Attack and Power, reducing the damage dealt by subsequent attacks. Second, a Djinni's effect cannot be used again until that Djinni is re-Set, which means either wasting a turn manually Setting the Djinni or using it to perform a Summon, after which the Djinn used must spend several turns Recovering before they automatically Set themselves. Either way, offensive Djinn cannot be repeatedly used as easily as Psynergy, making Diamond Dust and Diamond Berg more feasible for long-term combat. Alternatively, players may choose to combine both approaches: Unleash several offensive Djinn, perform a Summon, then use Diamond Dust and/or Diamond Berg to continue dealing damage while the Djinn are in Recovery.

By game
Golden Sun: The Lost Age: Piers will already know Diamond Dust by the time he joins the party. Meanwhile, Diamond Berg is considered to be Piers's ultimate Mercury-based offense. Enough Mercury Djinn can be found in the Great Eastern Sea for Piers to access the Captain class prior to entering Lemuria, making Diamond Berg an effective, if expensive, attack to use against the Avimander, though not Poseidon. It may also prove useful against Moapa and his two Knights, but its practicality begins to fade by the end of the game, though not as much as Odyssey's, due to the smaller number of high-powered Mercury-based Unleashes. Golden Sun: Dark Dawn: Amiti will know Diamond Dust when he joins the party at Ayuthay. The player will not gain the six Mercury Djinn necessary for the Aqua Lord class until exploring Morgal. As Amiti is a mage-style Adept, he is in a unique position, being the only mage-style Adept to know a physical-elemental attack in his base class. While his attack cannot get as high as Piers due to the weaker weapons he can equip, the series still provides him with a great deal of versatility. Although its PP cost hasn't gone down any, Diamond Berg is a more practical choice than it was in The Lost Age, due primarily to changes to the Unleash system that further reduce the likelihood of scoring damage-multiplying Unleashes. In addition, new methods for recovering PP help cushion the blow Diamond Berg deals to Amiti's PP pool.