Ranger Class Djinni Combination
The Ranger class is one of the powerful elemental caster classes available to your Jupiter Adepts Ivan and Sheba as well as your Mercury Adepts Mia and Piers. Players can turn their characters into a Ranger fairly early on but the class doesn't have much usefulness for boss fights until 25+ since it only gets one single target damaging ability and doesn't get its useful buffs until later in the game.
Mercury Adepts: 3 Mars; 3 Jupiter (Ranger)
Mercury Adepts: 4 Mars; 4 Jupiter (Bard)
Mercury Adepts: 5 Mars; 4 Jupiter (Warlock)
Jupiter Adepts: 3 Mars; 3 Mercury (Ranger)
Jupiter Adepts: 4 Mars; 4 Mercury (Bard)
Jupiter Adepts: 5 Mars; 4 Mercury (Warlock)
Depending on your playstyle determines if you should make someone into a Ranger or not. Most of their damage is AoE and aside from Slash/Volcano they don't get any single target damage. This means that for boss fights you'll primarily be debuffing and buffing your team.... Which is quite useful mind you especially since buffs stack in this game.
Here is a list of abilities that are available to a Ranger in game:
(Level 1) Slash: Hits a single target with 25 Power.
(Level 2) Douse: Hits 3 targets with 25 Power.
(Level 6) Ward: Raises the resistances of a single adept by 40. Stacks to a total of 80.
(Level 8) Volcano: Hits a single target with 45 Power.
(Level 10) Wind Slash: Hits 3 targets with 50 Power.
(Level 12) Drench: Hits 3 targets with 60 Power.
(Level 18) Bind: Prevents a single target's ability to cast Psyenergy.
(Level 22) Eruption: Hits 3 targets with 90 Power.
(Level 24) Resist: Raises the resistances of your entire party by 20. Stacks to a total of 80.
(Level 30) Sonic Slash: Hits 5 targets with 120 Power.
(Level 30) Deluge: Hits 5 targets with 120 Power.
(Level 33) Drain: Single target attack for 50 Power. Drains HP for damage inflicted.
(Level 34) Break: Removes the buffs on all enemies.
(Level 41) Psy Drain: Single target attack, has a chance to drain PP.
(Level 48) Pyroclasm: Hits 5 targets with 180 Power.