Deals dark damage that weakens an enemy's attacks and gradually reduces its HP.


Spell cost: 15 MP
Spell element: Dark
Magic skill: Dark Magic

Note: Automatons learn this spell automatically once they have the requisite magic skill. They do not need to use a scroll.


Casting Time: 1.5 seconds
Recast Time: 5 seconds

Other Uses

Resale Price: ~102 gil

How to Obtain

Auction House Category: Scrolls > Black Magic ( )


Price: 360 - 416 gil
Name Location Type
Aroro Port Windurst (H-8) Standard Merchant
Regine Port San d'Oria (J-8) Standard Merchant
Zaira Bastok Markets (H-5) Standard Merchant
  • Note: The availability of this scroll from these Merchants is subject to the condition that the nation where you're trying to buy it is ranked 1st or 2nd in Conquest.

Other Information

Effect Duration
1 Minute (60 Seconds)
Enemy Attack down effect
Attack is reduced by 27/512 (5.27%)
April 3, 2019 Version Update
"The attack down effect of the black magic spell Bio has been adjusted. Numbers in parenthesis represent the value when affected by the Corsair ability Dark Shot.
Name Pre-adjustment → Post-adjustment
Bio 5% → 10%(13%)
Bio II 10% → 15%(18%)
Bio III 15% → 20%(23%)"
Dia / Bio Priority 
Since Light and Dark are in opposition, whichever spell is higher level (requires a higher level job to use), overwrites the other. Casting Bio of the same tier as its Dia counterpart will result in the Dia status being removed (Dia and Bio do not stack). Example: If Dia is cast, and Bio is cast afterwards, Dia will be overwritten. If Dia II is then cast, Bio will be overwritten. If Bio II is cast, Dia II will be overwritten.
Bio III > Dia III > Bio II > Dia II > Bio > Dia


  • Dia should generally be used on high-defense mobs such as Crab.
  • Use of Bio in Campaign Battles counts toward Elemental Magic Damage in terms of rewards calculation, despite its primary use being that of enfeebling. The reward is based solely on the initial damage reported in the log, and not on the overall damage-over-time.