Platform: Windows
Date & Time:
Frequency: Always
Character Name: Jeanpaul and Gelenkia
Race: Hume M and Hume M
World: Sylph
Main Job: RUN and SMN
Support Job: WHM and WHM
Area and Coordinates: Zhayolm Remnants II, 5th floor
Party or Solo: Party
Monster Name: Battleclad Chariot
Steps:
  1. Enter Salvage (Zhayolm Remnants II) with two party members (RUN and SMN) to test the modifiers and potency of One For All
  2. Unlocked equipment and other pathos and travel to floor 5
  3. Spawn Battleclad Chariot and confirm that the weaponskill Discoid deals 4000 light magic damage shared between party members
  4. While wearing no other magic damage reduction gear or statuses, allow the monster to use Discoid on both party members while under the effect of One For All

Potency of One For All seems to be determined as 20% HP for each individual character at the time they gain the Magic Shield effect (ie: RUN with 2500 HP takes 500 less damage, SMN with 1500 HP takes 300 less damage). Unclear if it is intended to use each party member's HP for the calculation, or the HP of the RUN who activates the ability.

Thank you for looking into this matter.