Replekia System

The Replekia System repurekia shisutemu (レプレキアシステム) is a gameplay mechanic exclusive to Ar tonelico II: Melody of Metafalica that gets unlocked toward the end of the first storyline Phase regardless of the route chosen by the player, which consists of Cloche Leythal Pastalie singing the song METHOD_REPLEKIA/. in-battle to garner the support of all the IPDs that have joined Cloche's Fan Club for the Song Magic the Reyvateils are currently singing in order to greatly amplify its charge speed and attack power. Given this, using Replekia with a powerful Song Magic while having a large number of IPDs in Cloche's Fan Club can allow the player to finish any battle in just one attack.

Whenever it is used, the battle background will change to a black space filled with red and yellow speed lines with Infel Phira in Replekia Mode slowly rotating behind the player party, and the battle music will be replaced by METHOD_REPLEKIA/., the only exception to this being the two phases of the Ryuju battle.

Mechanics
The Replekia System can be always activated in battle provided the player has Cloche in their active battle party and has already seen the tutorial explaining its usage. To use it, the player must have the Reyvateils singing a Red Magic (offensive-type) song and make their vanguards use Harmonic-type attacks until Cloche's Harmonics level has reached Lv. 3, which is the highest possible level for the Reyvateils. Once they do this, a notification will be displayed near the bottom of the screen stating that Replekia can now be used and the "Replekia" option will be added to Cloche's battle commands in the battle menu. Upon selecting it, Replekia will be activated.

Replekia will then start gradually adding the power of the IPDs that have been recruited into Cloche's Fan Club until it reaches the player's current max number of recruited members, at which point the amplification in speed and power will gain its maximum intensity. It must be stated though that Replekia can only be used once per battle and that its duration will only be either until the player presses the Circle button to make the Reyvateils activate their Song Magic, or until they run out of MP and the song gets activated by itself.

Tutorials
A tutorial on the usage of the Replekia System is given right when the system and the Super Attacks are unlocked for the player's use during the first battle with ??? in Phase 1. As this battle is scripted, the player won't be able to do anything to ??? until they have fulfilled the conditions for activating Replekia and used it successfully, though there are some cases in which using Song Magic incorrectly might cause the tutorial to bug out and the game impossible to continue.

It's also worth nothing that during the tutorial, the player will be given a full 100 IPD chorus, allowing them to see Replekia's full power in action.

Connection with the Cloche Fan Club
As Replekia depends on the willingness of the IPDs to lend their powers to Cloche, this means that its effectivity will be reduced from its overall potential if the player doesn't go out of their way to recruit more IPDs into the fanclub by complying with their support requests, which go from saving specific Leaf amounts, defeating monsters from a species or watching certain talk topics between Croix and the girls or between the girls themselves. Once these conditions have been fulfilled to the point a IPD's support gauge reaches 100%, they will be available for recruiting by just visiting the location where their branch of the Fan Club is located. Cloche will also notify the player of this whenever they enter a city where a recruitable IPD has been made available.

Amplification
The Replekia System depends on the following variables to determine the amount of its amplification in-game: Burst Percentage, Number of IPDs recruited in the Fan Club and the Replekia Resistance value of the monsters, the latter being a hidden value all enemies have in their individual drop tables. The formulas are as follows:

Burst Percentage = Song Power Base

Replekia Burst Percentage = Song Power Base + Great Additional Song Power * IPD Number / 100

Replekia Damage = Replekia Burst Percentage + Replekia Burst Percentage * (IPD Number² + IPD Number) / (Replekia Resistance * 100) * 5

Thanks to this setup, each additional IPD provides an exponential increase in power and Burst speed to Replekia's amplification, allowing players to cause great damage even with a relatively small IPD support chorus.

Creation and Development
Tsuchiya envisioned the Replekia System as a rewarding form of collectionism and completionism for players, as instead of just allowing them to collect useless trophies or somesuch, he wanted the collectibles to have more of a positive impact on the player's experience by allowing them to gain strength for every piece of the set they collected. That's why it was decided to make the 100 IPDs, each with their own unique portraits and personalities, and add it as part of the Replekia System due to the function METHOD_REPLEKIA/. has in-setting of joining together the feelings of multiple people. He originally wanted to put in a million of IPDs, but settled down on it being impossible and reduced it to 1000. He afterwards reduced to its definitive 100 number thinking 1000 would still be too much and too hard to implement properly.

Additionally, making METHOD_REPLEKIA/. override all the other battle BGMs was something that gave him and his team a lot of trouble to implement due to hardware limitations and programming difficulties, but it ultimately served as the basis for the RAH System that was used in Ar tonelico Qoga: Knell of Ar Ciel.