Hydra enemy line

The Aqua Hydra, Hydra, and Pyrodra are species of monsters randomly battled in Golden Sun: The Lost Age and Golden Sun: Dark Dawn. These monsters, resembling large three-headed sea serpents, are palette-swapped variants of each other that have differing levels of power and defense and are fought in different locations in the games. This monster line includes one boss.

Aqua Hydra
The Aqua Hydra is a giant-sized variant with light blue scales and a light-green underbelly, and is a boss in Golden Sun: The Lost Age. It uses these battle commands:
 * Raging Flood: Used 88 out of 256 times, this is a Monster Skill where the monster summons a water wave from behind itself to wash through the Adepts (the visual is similar to the Dreamtide unleash effect of the Pirate's Sword), dealing a Mercury-based attack with a power rating of 110 and hits every party member. Unlike most forms of offense in the game, this attack always hits every Adept with an equal amount of force. The Aqua Hydra uses this with a Mercury power rating of 115. The main ability that makes the Aqua Hydra a powerful threat of a boss.
 * Triple Chomp: Used 53 out of 256 times, this is a Monster Skill where the monster bolts forward and strikes a targeted Adept with three strong blue-colored bites in a row, dealing a Mercury-based attack equal to its normal physical attack multiplied by 2.4. The Aqua Hydra uses this with a Mercury power rating of 115.
 * Rising Venom: Used 35 out of 256 times, this Monster Skill has the monster lobbing a small mount of glowing green poison at a targeted Adept, dealing a Mercury-based attack equal to its normal physical attack with an additional 30 damage points, and there is a chance that the Adept will be afflicted with Poison. The Aqua Hydra uses this with a Mercury power rating of 115.
 * Drench: Used 29 out of 256 times, this is a Psynergy spell that drops moderately large spheres of water onto the opposition, dealing a Mercury-based attack with a power rating of 60 and a range of 3. This ability consumes 10 of its user's PP, meaning that it is able to use Drench exactly seven times throughout the battle. The Aqua Hydra uses this with a Mercury power rating of 115. This move is actually much less damaging than Raging Flood, and exists only to give the party somewhat of a break from its constant use of that monster skill and make the boss a little more manageable.
 * Attack: Used 28 out of 256 times, this is this monster's standard physical attack.
 * Slaver: Used 23 out of 256 times, this is a Monster skill where the monster projects out of its mouth a lot of multi-colored saliva all over the party of Adepts (perhaps "Slaver" is a corruption of "saliva" that occurred during translation of the game), and each affected Adept may have his or her Defense rating temporarily lowered by 12.5%. In other words, it works exactly like the Debilitate Psynergy, but has a range of 5 instead of 3.

In Golden Sun: The Lost Age it is a mandatory battle that takes place in the Lemurian Ship as it is beached at East Indra Shore. After Piers has joined the party, the player is to eventually return to the ship and explore it, fighting Aqua Jellies along the way. In a room with a bunch of crates and six of these monsters around them, interact with the center Jelly standing on one of the crates and the other five Jellies will suddenly jump all together into the sixth, and they will merge and metamorph into the single beast which you immediately fight as a scripted boss encounter.

This can be quite a challenging boss encounter, because of both its powerful full-party offenses and its large amount of HP. If you've collected all four available Mars Djinn up to this point (Cannon, Spark, Kindle, and Char), keep them Set onto Jenna so that she is in the Hex class, which grants her the Aura Psynergy series. If she is at least level 16, her Healing Aura Psynergy will be an immense help for curing the party each time the Aqua Hydra uses its Raging Flood move. Using Jenna as a designated healer for this boss encounter, however, means that you'd be somewhat hard pressed to capitalize on the boss' weakness to the Mars Element, since a Meteor summon using all four of the Mars Djinn would do around 800 damage to the boss in one blow. Of course, using a different setup that would allow someone like Sheba to use Wish Well while Jenna summons Meteor should be considered as well. Any Oil Drops that might be in your possession would be good to use up in this battle because they are essentially free Flare Storms that can be used by any Adept.

Hydra
A Hydra is a normal-sized variant with purplish-pink scales and a light-orange underbelly. The Hydra uses these battle commands:
 * Attack: Used 4 out of 8 times, this is this monster's standard physical attack.
 * Triple Chomp: Used 2 out of 8 times, this is a Monster Skill where the monster bolts forward and strikes a targeted Adept with three strong blue-colored bites in a row, dealing a Mercury-based attack equal to its normal physical attack multiplied by 2.4. The Hydra uses this with a Mercury power rating of 115.
 * Slaver: Used 2 out of 8 times, this is a Monster skill where the monster projects out of its mouth a lot of multi-colored saliva all over the party of Adepts, and each affected Adept may have his or her Defense rating temporarily lowered by 12.5%. In other words, it works exactly like the Debilitate Psynergy, but has a range of 5 instead of 3.

In Golden Sun: The Lost Age it is one of the "stock" monsters fought all throughout the Great Western Sea while sailing, as well as when sailing in the Northern Reaches. The Hydra is the slowest of the monsters it is fought alongside with, and is moderately sturdy in a way that is far outperformed by the Turtle Dragon. Quite simply, the only thing to keep in mind about this specie is the occasional Triple Chomp for massive damage.

Pyrodra
A Pyrodra is a normal-sized variant with pink scales and a light-blue underbelly. The Pyrodra uses these battle commands:
 * Attack: Used 3 out of 8 times, this is this monster's standard physical attack.
 * Triple Chomp: Used 2 out of 8 times, this is a Monster Skill where the monster bolts forward and strikes a targeted Adept with three strong blue-colored bites in a row, dealing a Mercury-based attack equal to its normal physical attack multiplied by 2.4. The Pyrodra uses this with a Mercury power rating of 115.
 * Fire Breath: Used 2 out of 8 times, this Monster Skill has the monster generating a mass of fire at the party of Adepts, dealing a Mars-based attack with a power rating of 180 and a range of 3 (the Adepts at either side of the specifically targeted Adept will only take 50% of the attack's force, instead of the normal 80%, however). The Pyrodra uses this with a Mars power rating of 85.
 * Rising Venom: Used 1 out of 8 times, this Monster Skill has the monster lobbing a small mount of glowing green poison at a targeted Adept, dealing a Mercury-based attack equal to its normal physical attack with an additional 30 damage points, and there is a chance that the Adept will be afflicted with Poison. The Pyrodra uses this with a Mercury power rating of 115.

In Golden Sun: The Lost Age it is randomly fought throughout the deeper, tougher portion of Treasure Isle. The Pyrodra ties with the Puppet Warrior as the slowest monster in that area, and while that monster has a powerful skill with an added effect that might lower an Adept's HP down to 1, the Pyrodra merely has powerful skills. Triple Chomp, as always, can cause a lot of damage individually. Even though its name and monster skill suggest a more fire-type monster than the previous versions, it is still a very water-type monster with merely an extra fire attack, and fire in general is still its weakness in fact. Being the source of Salamander Tails makes it either farmed often or the target of Random Number Generator manipulation for guaranteeing it drops it.

Hydra
A Hydra is a varant with brown scales and a green underbelly. A Hydra can use the following battle commands:
 * Attack: Used 6 out of 8 times, this is this monster's standard physical attack.
 * Mesmerize: Used 1 out of 8 times, this is a Monster Skill that has the battle text read "Hydra stares... Mesmerize!" as the monster spews large mounds of light purple gunk on the party of Adepts, possibly reducing the Defense rating of each affected Adept by 12.5%; it has a range of 5. This appears to be the Slaver monster skill from the previous game, just renamed.
 * Triple Chomp: Used 1 out of 8 times, this is a Monster Skill where each of the monster's heads attacks a single Adept, dealing a Mercury-based attack equal to its normal physical attack multiplied by 1.7. The Hydra has a Mercury Power rating of 115 to work with this attack.

Hydras are fought in Barai Temple.

Aqua Hydra
An Aqua Hydra is a varant with blue scales and a light blue underbelly. An Aqua Hydra can use the following battle commands:
 * Attack: Used 4 out of 8 times, this is this monster's standard physical attack.
 * Mesmerize: Used 1 out of 8 times, this is a Monster Skill that has the battle text read "Aqua Hydra stares... Mesmerize!" as the monster spews large mounds of light purple gunk on the party of Adepts, possibly reducing the Defense rating of each affected Adept by 12.5%; it has a range of 5.
 * Triple Chomp: Used 1 out of 8 times, this is a Monster Skill where each of the monster's heads attacks a single Adept, dealing a Mercury-based attack equal to its normal physical attack multiplied by 1.7. The Aqua Hydra has a Mercury Power rating of 115 to work with this attack.
 * Rising Venom: Used 1 out of 8 times, this Monster Skill has the monster lobbing a small mount of glowing green poison at a targeted Adept, dealing a Mercury-based attack equal to its normal physical attack with an additional 30 damage points. This attack also has a chance of inflicting Poison.
 * Drench: Used 1 out of 8 times, this is a Psynergy spell that drops moderately large spheres of water onto the opposition, dealing a Mercury-based attack with a power rating of 60 and a range of 3. This ability consumes 10 of its user's PP; the Aqua Hydra's PP meter is sufficient for two castings.

Aqua Hydras are fought in Belinsk Ruins.

Pyrodra
A Pyrodra is a varant with wine-colored scales and a bluish underbelly. A Pyrodra can use the following battle commands:
 * Attack: Used 5 out of 8 times, this is this monster's standard physical attack.
 * Fire Breath: Used 1 out of 8 times, this Monster Skill has the monster generating a mass of fire at the party of Adepts, dealing a Mars-based attack with a power rating of 90 and a range of 3 (the Adepts at either side of the specifically targeted Adept will only take 50% of the attack's force, instead of the normal 80%, however). The Pyrodra has a Mars Power rating of 115 to work with this attack.
 * Triple Chomp: Used 1 out of 8 times, this is a Monster Skill where each of the monster's heads attacks a single Adept, dealing a Mercury-based attack equal to its normal physical attack multiplied by 1.7. The Pyrodra has a Mercury Power rating of 85 to work with this attack.
 * Rising Venom: Used 1 out of 8 times, this Monster Skill has the monster lobbing a small mount of glowing green poison at a targeted Adept, dealing a Mercury-based attack equal to its normal physical attack with an additional 30 damage points. This attack also has a chance of inflicting Poison.

Pyrodras are fought in Burning Island Cave.

Cultural References
Origin: Greece

The Hydra (also known as the Lernaean Hydra) in Greek mythology was an ancient serpent-like water beast that had multiple heads and toxic breath. The Hydra of Lerna, which was slain by Hercules for his Twelve Labors, lived in the Spring of Amymone. Its blood was then used by Hercules to make poisoned arrows for future tasks.