So this has been asked a few times in various places and in PMs, so I thought I'd just make a general post to explain why this stuff happens. This happens because of the way things were setup during the revamp, some runes "shared" an "Upgrade Group" - so when you change one, the upgrades for any other champ using that same "Upgrade Group" also changes - but the database doesn't tell you this happens, so you have no idea. Whenever I have seen this I have adjusted it so that they no longer share the upgrade line, but there are still lots that do, unfortunately. For example, if you see Champs that have Regen 1/2/3, they are probably all using the same shared "Upgrade Group", and if you change Regen 1 to Burn 1 in that case then all champs using that that upgrade group will also be changed. It's extremely annoying. In this case, the Nefari Dragon also has the same upgrade line of Burn 1, Flamestrike and Flame Nova - so when he was changed to have Burn 1, it also impacted the Arcanis. The same thing happened with Scarlet Wing too, which is how it ended up with Burn on the 2nd line as well, but he's been fixed already for next patch.
So please, do point it out when something like this happens and it doesn't make sense to you, because they are really easy to miss on my end
Scarlet Wing has burn 1 and burn 2 in different uppgrade paths which seems iffy. Unfortunately that is also borderline its best build.
It's not his best because you're paying for both abilities and only getting one; even if it is cheaper it isn't efficient as you're paying 3 nora(Burn 1) for absolutely nothing. .
As mentioned, all 3 of the champions (Scarlet Wing, Nefari Dragon and the Jangar Arcanis) all shared an upgrade line, thus, when the Nefari Dragon was edited to have Burn in the 2nd line, the other 2 inadvertently got it as well.