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Date & Time: Since 6.45
Frequency: Always
World name: Brynhildr
Character name: Mahdi Welter
Monster name: Oracle of Darkness
Class/Level: 80 BLU
Party or solo: Party
In-game time: Any
Area and coordinates: Eden 12 Phase 2 Savage

Steps:
1. Early into the fight, Oracle will cast Spell in Waiting. And then will cast Dark Water or Dark Eruption for stacks or spreads respectively. She will then cast Spell in Waiting again and then finally Dark Water or Dark Eruption, whichever she did not previously cast.
2. When the first Spell in Waiting is resolving, when the circular dice countdown appears, cast Cold Fog. When the spell resolves for damage to the player, Cold Fog will become White Death.
3. At roughly this period of time the next spell in waiting will be placed as debuffs on players. If you had cast Cold Fog and it became White Death you will no longer have the Spell in Waiting (Water or Eruption) over your head. Once the countdown from 5 starts it will reappear over your head.

Note: The Debuff never goes away and the mechanic works correctly, just the visuals over a players head will not appear. This is not just a visual bug on ONLY the player using cold fog but a visual bug will appear even for players who do not use it when they look at players that did use Cold Fog.

While this is not my video, it does show the bug.
https://youtu.be/rNKkrwT7iZc?t=2612
Notice that it is Dark Eruption First, and the Spell in Waiting for it is over their heads the whole time. But for the next part both players with the Stack used Cold Fog and you cannot see the stack marker over their head until the countdown starts.