Thanks to Suede, CottonC, and salien from Discord for helping me test these.

Stackable active effects

As a general rule, same active effects (buff or debuff) do not stack. There are some exception to these:

• Enable multicast (ability)
• Enable skill
• Mod boost

Majority of those skills do stack in practical situation and you can have more than 1 instances of them. However, we found that these skills have a stacking ID parameter. Skills with the same active effect and identical stacking ID do not stack and will overwrite previous effect. They will still layer like regular effects do, except with the newest, not necesarily the strongest, at the top.

If a stacking ID is null (not specified), it defaults to 0. You can still have different effects with the same stacking ID. For example an "enable skill" with an ID of 1, and a "mod boost" with an ID of 1, will stack.

If a unit is queuing an enabled skill/multicast and another unit is overwriting it, you can still use the queued skill/multicast. But you won't be able to use repeat/reload next turn.

Note that multicast (ability) is different than multicast (magic), which weren't tested.

We are currently unsure on how to add this to the wiki. They could be added to notes. But that would involve manual work, and not really visible. They could be added to the skill wording like (Stack #136-1001) Increase modifier (x) for # turn to caster: [skills] but it might confuse people, and a lot of bloat for just a few notable exception.

For now you check them on aEnigma's data dump. I've listed notable exceptions below.

Enable multicast (ability)

Effect ID: 98
Stacking ID: 9th parameter

Right now, literally all of them on GL has the same stacking ID, and don't stack. On JP, unit like Trance Terra received changes on her stacking ID, and able to activate both multicasts.

Notable exceptions:

• Trance Terra: Successor - Maduin's Power (W-cast) and Chaos Chain (Q-cast) overwrites each other. This is fixed on JP.
• Beryl: Seraphic Call (W-cast) and Seraphic Redemption (T-cast) overwrites each other. A long time ago gumi released an issue report describing this bug, but it was never fixed.
• Sylvie: Hare I go! (W-cast) can be given to any unit. Be warned that this will overwrite any existing enabled multicast on that unit.
• Paladin Cecil: See below.

Enable skill

Effect ID: 100
Stacking ID: 6th parameter

Notable exceptions:

• Christine: Ice Shards can be given to any unit. It has a stacking ID of 0, which might or might not overwrite any existing enabled skill on that unit.
• Paladin Cecil: See below.

Sylvie, Summer Fina & Lid, and Qin enabled skills have unique stacking IDs and do not suffer from overwriting issue.

Mod boost

Effect ID: 136
Stacking ID: 7th parameter

Notable exceptions:

• Citan: None of his mod boosts stack.
• Warrior of Light Bartz: All of them stack, except for his "leveling up" skills, which you can only have 1 of:
  • (3x) ジョブレベルアップ：レベル2
  • (4x) ジョブレベルアップ：レベル3
  • (5x) ジョブレベルアップ：ジョブマスター★★★

How Paladin Cecil works

Paladin Cecil: https://exvius.gamepedia.com/Paladin_Cecil/JP

If you equip his S/TMR, he will start a battle with his PLD skills. Among those skills is "Into the Dark", which enables his DRK skills. Once switched to DRK, you can switch back to his PLD skills by using "Into the Light". These skills are enabled permanently unless switched.

His PLD and DRK skills, including the multicast, is not stackable, and will overwrite each other. If he gets revived he will start again with his PLD skills. If you don't use his S/TMR, you get none of these skills.

On an unrelated note, Cecil can maintain a permanent uptime of 75% general mitigation, or semi permanent if you use his LB. What many don't realize is the power difference over 50% general mitigation, which is a standard now on JP. 75% is twice as much eHP than 50%. This is the equivalent of Cecil being able to guard while still casting something else.

Qin's auto-cast skills re-tested

Back then we found that Qin's auto-cast skills persist after death. My hypothesis were either a bug or Qin's unique parameter on these skills is the cause of it.

After re-testing, we find that Qin's skill is now no longer persisting through revival, so it was likely a bug. We have no idea what the unique parameter on Qin's skill is for.

King Edgar of Figaro's skill is also tested, and works as expected.