No, Poison will not stack with itself - if you are looking to have a double DOT** of just Poison cast on a mob. It will stack with other Dark base BLM DOT Enfeebling** spells like Slow, Blind and Bio.
In fact Bio and Poison is usually the gold card stand used by most BLMS. Just remember that Dark DOT or Enfeebling will NOT stack with other types of magic like Light.
If you cast Poison then Dia, Dia will cancel Poison.** I know this was a simple question but to really understand your magic and JOB - there is a bit of research involved. My firsts jobs leveled to 99 were 99WHM/99BLM over 9 years ago. I still had a lot to learn about the jobs Skyfiredancer (talk) 02:00, October 14, 2018 (UTC)
- Damage Over Time https://ffxiclopedia.wikia.com/wiki/Damage_Over_Time
- Enfeebling spellings. https://ffxiclopedia.wikia.com/wiki/Category:Enfeebling_Magic