Vine

Vine (アイヴィ Ivy) is a Venus Djinni found   throughout the Golden Sun  series.

Vine is the fourth Venus Djinni in the original Golden Sun and the sixth Venus Djinni in Golden Sun: Dark Dawn, and can also be acquired in Golden Sun: The Lost Age. Although it is not the party's fourth Venus Djinni in The Lost Age,  Vine is still ordered as the fourth  Venus Djinni when equipped to  characters. Because it is not available until after most other Venus  Djinn can be found, however, the separate  Djinn list viewable with the  Select button from the status screen lists  Vine and all other Venus  Djinn from Golden Sun after all of the  Djinn introduced in The  Lost Age. According to this order, Vine is the fifteenth Venus Djinni in The Lost Age rather than the  fourth, but this order has no  influence elsewhere in the game.

Basic description
When Set, Vine increases its Adept's base HP by 12, base PP by 4, base Defense by 3, and base Luck by 1.

When Vine is unleashed in battle, all enemies' Agility ratings are lowered down to 50% of their normal values, the lowest value the Agility rating can be debuffed down to.

In  Golden Sun and The Lost Age, Vine's unleash animation visually resembles the user summoning a glowing, transparent  image of a Venus Djinni that disappears immediately above the enemy group, and then a group of wriggling green vines briefly sprout out of the ground at the position of the enemy party and then retract back into the ground. In Dark  Dawn, the 3D model of Vine appears and disappears briefly, and a small, yellow-glowing fissure appears under the enemy's feet for a moment. Then a small collection of green, leafy plants grow out of the fissure and hold for a moment.

Locations
Golden Sun: Vine is a Djinni that is randomly encountered in a specific area of the  overworld that otherwise appears to be pointless scenery. Thus, it is very often missed by players playing the game the first time without any  outside information. The battle with Vine may ensue in place of a random battle in the circular "island" to the immediate northwest of  where you exit Lamakan Desert, led to by the upper of two bridges that are immediately visible. It can also appear on the larger island just north of crescent shaped one. Furthermore, it may also appear on the strip of land north of the exit between the mountains and the river.

Golden Sun: The Lost Age: Players can transfer data from Golden Sun to The Lost Age, but even if they don't, Vine will be among the Djinn Isaac's party has with them when they join forces with Felix's party late in the game.

Golden Sun:  Dark Dawn: Vine is found late in the Teppe Ruins, in the room before the room where Sveta is met. It will run away into tall grass, and will run away from the player through the grass for as long as the player tries to catch it, so the player must walk up a ledge to the left of the room and move an earth pillar up one tile into the grass. With this pillar in place, when the player next chases Vine, it will encounter the pillar and position itself up north in the open, and you can grab it without fighting it.

As an opponent (Golden Sun)
Statistically, Vine has 421 HP, 30 PP, 175 Attack, 45  Defense, 91 Agility, and 10 Luck. Like all other Venus Djinn that are fought, in terms of resistance, it has a Venus Resistance  rating of 193, Mercury and Mars Resistance ratings of 100 each, and a  Jupiter Resistance rating of 25, and in regards to its abilities it uses  its available Venus-based attacks with a Venus power rating of 125.

Vine can use the following battle commands:
 * Gaia: Used 53 out of 256 times, this is a Psynergy spell that causes the  ground beneath the enemy to open up and engulf the party in a wide  reverse shower of Venus energy and medium-sized boulders, dealing a  Venus-based attack with a power rating of 40 and a range of 3. This  ability consumes 7 of its user's PP.
 * Mad Growth: Used 47 out of 256 times, this is a Psynergy spell that  causes a group of thorny vines to erupt from the ground and through the  Adepts for a short time, dealing a Venus-based attack with a power  rating of 60 and a range of 3. This ability consumes 10 of its user's  PP.
 * Quake Sphere: Used 41 out of 256 times, this is a Psynergy spell that prompts three rectangular sections of  ground underneath the party to jolt upward and retract into the ground  quickly thrice in succession, bouncing each Adept three times, dealing a  Venus-based attack with a power rating of 65 and a range of 7. This  ability consumes 15 of its user's PP.
 * Briar: Used 35 out of 256 times, this is a Psynergy spell that causes a series  of quite large spiked vines to grow out of the ground quickly to assault  the opposition, dealing a Venus-based attack with a power rating of 70  and a range of 3. This ability consumes 11 of its user's PP.
 * Clay Spire: Used 29 out of 256 times, this is a Psynergy spell that  causes three thick stalactites to fall out of the sky and shatter onto  the party, dealing a Venus-based attack with a power rating of 85 and a  range of 3. This ability consumes 13 of its user's PP.
 * Attack: Used 28 out of 256 times, this is this monster's standard physical attack, but for this monster it is counted as a  Venus-based attack rather than a non-elemental attack.
 * Flee: Ued 23 out of 256 times, this enemy has the ability to attempt to Flee  the battle, thereby ending the battle if successful without rewarding  you with the associated EXP, Coins, and the Djinni itself. Since this is  a randomly battled overworld Djinni, however, it can be very quickly  fought again just by running around in the same area you first fought it  in.

When defeated, Vine yields 230 EXP and 277 Coins, and the Vine Djinni is added to your  party's Djinn collection. If you fell it with an offensive Jupiter Djinni like Smog, its rewards increase to 299 EXP and 360 Coins.

It is possible to have four Jupiter Djinn in your collection at this  point, so having Ivan summon Thor with them will deal over 400  damage to Vine in one blow - practically a one-hit KO.

Analysis
General: Vine being an effect that halves all enemies' agility ratings can be thought of as equivalent to an effect that doubles the whole party's Agility ratings, which other Djinn can do. However, there is one additional benefit that halving enemy agility has: if an enemy has the Break Psynergy, they can't remove their own statistical drops the way they can remove a party's self-inflicted statistical buffs. This essentially lets the entire party move before a particular boss enemy, rather than only part of the party, while the other part of the party moves after the boss' action(s) the current turn. This can be situationally useful in letting an Adept with a group-healing effect use their healing before a boss can fell an Adept low on HP.

By game
Golden  Sun:  Vine works particularly well against Deadbeard, who ordinarily removes all buffs you cast upon yourself with Break but does not have any specific measures to remove negative effects from himself. Deadbeard has an agility rating to speak of, so unleashing Vine can be quite useful if some of your party members do not act before Deadbeard's first attack in the turn.

Golden  Sun: The Lost Age: When Isaac's party joins Felix's party along with their returning Djinn, Vine's ability makes it a second Mud, a Venus Djinni found in the early-middle of that game with the exact same effect. The two Djinn are usable interchangeably for the same situational purposes.

Golden  Sun: Dark Dawn: In general, Agility-modifying effects may not be as useful in Dark  Dawn as in previous games because with equipment like the  Zol Ring, your party is more likely to move before your opponents  anyway. This makes Vine one of the less useful Djinn in the game.

Name Origin
A vine is a type of plant characterized by climbing up trees or other surfaces as they grow. Ivy is a type of vine that often known to climbs up walls of buildings, but is essentially a  synonym to a vine.