Luff

Location
Luff is located in Babi Lighthouse, in a lone platform in the center of a large abyss where it appears unreachable. To get to it, in the screen outside the main building with all the wounded workers, climb down the ladder to the left, use Move to move the left pillar in the underground one space left, climb back up, climb down the ladder underneath the pillar to the right, use Move to move the right pillar one space left, make your way up to back outside where a small plant is visible, cast Growth on the plant, climb up and slide down to the elevated entrance into the building, and slide down the one slide of three you're able to reach in the room you immediately appear in. You will drop down to Luff's position. Save your game, then attempt to acquire it through battle.

As an opponent
Statistically, Luff has 688 HP, 62 PP, 302 Attack, 85 Defense, 177 Agility, and 21 Luck. Like all other Jupiter Djinn that are fought, in terms of resistance, it has a Jupiter Resistance rating of 193, Mercury and Mars Resistance ratings of 100 each, and a Venus Resistance rating of 25, and in regards to its abilities it uses its available Jupiter-based attacks with a Jupiter power rating of 125.

Luff can use the following battle commands:
 * Wind Slash: Used 53 out of 256 times, this is a Psynergy spell that shoots out a moderately large purple air swath at each Adept, dealing a Jupiter-based attack with a power rating of 50 and a range of 3. This ability consumes 9 of its user's PP.
 * Tornado: Used 47 out of 256 times, this is a Psynergy spell that causes two whirlwinds laced with electric charges to spin through the party, dealing a Jupiter-based attack with a power rating of 80 and a range of 5. This ability consumes 14 of its user's PP.
 * Blue Bolt: Used 41 out of 256 times, this is a Psynergy spell that causes two thick purple lightning bolts to strike at the party, dealing a Jupiter-based attack with a power rating of 90 and a range of 3. This ability consumes 14 of its user's PP.
 * Shine Plasma: Used 35 out of 256 times, this is a Psynergy spell that causes a three large bolt of purplish lightning bolts to strike at the party, dealing a Jupiter-based attack with a power rating of 100 and a range of 5. This ability consumes 18 of its user's PP.
 * Destruct Ray: Used 29 out of 256 times, this is a Psynergy spell that causes an array of thick purple lightning bolts to thoroughly assault the party, dealing a Jupiter-based attack with a power rating of 150 and a range of 3. This ability consumes 21 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 Jupiter-based attack rather than a non-elemental attack.
 * Flee: Used 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.

When defeated it yields 677 EXP and 506 coins and the Luff Djinni is added to your party's Djinn collection. If you fell it with an offensive Venus Djinni like Flint, its rewards increase to 880 EXP and 657 Coins.

Even though this is the last fought Djinni in the game, and thus should be very easy to blow away with full-powered summons in one turn, the amount of effort spent getting here demands that you save your game before attempting to get it, lest it happens to flee.

Description
When Set, it increases base HP by 13, base PP by 4, base Agility by 4, and base Luck by 1.

When Luff's battle effect is used, the target's Psynergy is temporarily sealed, but with full accuracy compared to the Bind Psynergy that often misses. It is identical to the TLA Mercury Djinni Rime.

Ability analysis
In Golden Sun, Luff is the one Djinni that is a fully accurate version of Bind, which certainly makes it far more valuable than Bind. There are only specific cases where this can be useful, though, since it only prevents an enemy from using Psynergy while not limiting its ability to attack and use Monster Skills. Easily the greatest example of this being useful, though, is in the Deadbeard boss fight, because every one of Deadbeard's battle commands that is not its physical attack is a Psynergy spell that either deals mass damage or buffs himself. The Psynergy seal typically lasts two turns, so the Adept that has Luff (preferably Ivan as he is meant more as a supporting Adept anyway and can easily have the necessary higher agility rating than Deadbeard) can use it on the first turn, then Set it back on the second turn, and repeat ad infinitum so that the other three Adepts can battle Deadbeard safely throughout the whole battle while Deadbeard can only launch un-bolstered whacks.

In The Lost Age, when Isaac's party joins Felix's party along with their returning Djinn (granted that Password data transfer is in effect), Luff's effect makes it a second Rime, a Mercury Djinni found later in the game in Ancient Lemuria. However, enemies with Psynergy abilities that would be worth using Luff/Rime on to limit their options meaningfully remain few, if any, and there isn't even a Deadbeard-like boss that would be limited strictly to a physical strike with this. Whereas there are many ways where using one of these on an enemy would be the opposite of beneficial; on Dullahan, for example, you'd be preventing him from using his comparatively harmless Psynergy spells and forcing him to only use his extremely powerful monster skills like Formina Sage and the summon Charon.

Name Origin
A luff is the vertical edge of a sail that is closest to the direction of the wind. Wind is associated with all Jupiter Djinn.