Justine and Caroline Fusion guide (The Strength Confidant)

Instructions on how to fuse the required personas with the skills needed for the Strength confidant. Also mentioned is the benefits of doing the Strength confidant.
Source [samurai-gamers.com]

Rank 1

Unlocks

Group Guillotine - Allows fusions involving 3 personas.

Requirements

Jack Frost with Mabufu

Method 1 : Fuse Silky (Priestess) and Berith (Hierophant).
Method 2 : Fuse Kelpie (Hermit) and Succubus (Moon).
Method 3 : Acquire Jack Frost at Madarames Palace or Mementos’ Path of Chemdah Level 3/4.

Any of these methods will work as Jack Frost learns Mabufu at level 12.
Example:

Rank 2

Unlocks

Nothing

Requirements

Ame-no-Uzume with Frei

Method 1 : Combine level 5 Caith Sith (Magician), level 7 Succubus , and a Frei Skill Card. You can obtain the Skill Card by itemizing Makami (Temperance).

Method 2: Fuse level 16 Suzaku (Sun) with a level 9 Berith (Hierophant).

Rank 3

Unlocks

Lockdown - Allows a persona in Lockdown to gain resistance skills

Requirements

Flauros with Tarukaja

Method : Fuse level 9 Berith (Hierophant), level 17 Orobas, and level 16 Eligor with Tarukaja.

Rank 4

Unlocks

Nothing.

Requirements

Phoenix with Counter

Method - Fuse level 2 Jack o’ Lantern (Magician) and Hua Po (Hanged Man) to get Yaksini. Fuse Level 20 Yaksini (Empress) and level 9 Kelpie (Strength) to get Phoenix with Counter.

Rank 5

Unlocks

Special Treatment - Allows you to pay to fuse personas higher than your current level

Requirements

Setanta with Rakukaja

Method : Fuse Silky (Priestess) with Lamia (Empress) to get Setanta with Rakukaja.

Rank 6

Unlocks

Nothing.

Requirements

Neko Shogun with Dekaja

Method : Anzu (Hierophant) learns Dekaja at level 28. Then, fuse Anzu (Hierophant), Kodama (Star), and Sudama (Hermit) inherit Dekaja.

Rank 7

Unlocks

Nothing.

Requirements

Lachesis with Tetraja

Method : Fuse level 29 Principality (Justice) with Tetraja and level 23 Sandman (Magician) to obtain level 36 Thoth (Emperor) with Tetraja. Fuse Thoth with level 25 Anzu (Hierophant)

Rank 8

Unlocks

Guillotine Booster - Allows fusions involving 4+ personas

Requirements

Hecatoncheires with Masukunda

Method : Lilim learns Masukunda at level 34. Then, fuse level 34 Lilim (Devil) and level 25 Anzu (Hireophant) while inheriting Masukunda.

Rank 9

Unlocks

Nothing

Requirements

Bugs with Samarecarm

Method : Hariti (Empress) learns Samarecarm at level 41. Then, fuse Hariti (Empress), Pixie (Lovers), and Pisaca (Death) while inheriting Samarecarm.

Rank 10 (MAX)

Unlocks

VIP Treatment - Gives a discount for Special Measures

Requirements

Seth with High Counter

Method 1 : Option #1: This can be earned as a skill card from the Mementos rank B mission request, “The Killer who takes out the Trash”.
Make Fortuna (Fortune) and Grimehkala (Moon) fuse to make Horus. Then fuse, Isis (Priestess), Thoth (Emperor), Anubis (Judgment), and Horus (Sun) to acquire Seth. Use skill card on Seth after fusion.
Method 2 : Option #2: Fuse for Cerberus. It learns High Counter at level 57. Fuse then with Horus to get a Skadi with High Counter. Then, fuse the Skadi with a Silky to get an Isis with High Counter (Credits to Minmo).
Method 3 : Option #3: Get Dakini which learns High Counter at level 52. Fuse Dakini (Empress) with High Counter to Ame no Uzume (Lovers) to craft Anubis with High Counter. Merge Anubis with the three other personas mentioned above to get Seth.

misc.

Here[chinhodado.github.io] is a very useful website for fusing personas, it shows what personas you need and at what level.

[Twitchiopolis]

Itemize Ose during an alarm to get High Counter card aswell