>>6 update. Poison didn't help after applying 3 stacks. Tried more stacks but they wouldn't apply. My guess is there is a super armour barrier that might allow you to push through on damage if you can maybe breach past 99 damage in a turn. Either that or they're just hard coding attacks to 0 damage. Something I could not try is AOE damage from tiki fire breath attacks. Those aren't exactly the same damage enemies normally take as it happens out of a combat turn similar to fire damage.

Veyle can be damaged by environmental effects like Fire. Problem is this isn't a kill condition as environment damage can only leave an enemy on 1 HP. So using someone with a DLC bracelet and Edelgard you can use the fire gambit to burn the floor beneath Veyle. (you'll likely have her stuck at 2HP/12HP unless you can refresh your engage) 2HP example: https://www.reddit.com/r/fireemblem/comments/10m755g/feengagespoiler_when_your_elabo Still need to do some poison testing

>>4 Nah, same result. Spent 15 minutes firing electric lazers at her and did no damage. Thank you for trying as well.

>>3 We've done our own testing as well and even after a 7xChain attack, there was still no damage dealt to Veyle! Our guide has been updated with this info, but if your testing ends up having different results, we'd love to see a picture or video of it!

>>2 Dang, I am working on grinding a second account with the dlc to maximize my stats just to test this. Thanks for the info.

>>1 I beat both the dragons but none of my units could get any damage on veyle

What happens if you are able to beat veyle and the dragon things? I was able to beat everything except those three.