Someone, Cratol I think, has a ring that provides advantage on Initiative. Poljen as a barbarian gets advantage on Initiative for hitting 7th level I believe. As for Cratol's advantage on attacking, if he is on the opposite side of the dragon from Poljen, he gets advantage. Anyone in melee gets that bonus. Of course it is particularly useful for rogues, but advantage helps anyone. At least that is my understanding of the rules.
I'd offer more exact details on where Zarra is, yet whenever I go to maps it doesn't appear to have what you are talking about/ I go there and I see the old cultist cave map as well one other without any details… I can't tell where it is for and there is no positioning details for anything.
Perhaps the map is somewhere else and I forgot where you put them.
My apologizes for forgetting, about how many feet is each square? I got into the bad happen of not using the map often, so I don't remember many of the important details. For this battle though, I can't see how I'd be able to do without… especially since the Dungeon Master asked for a check of position.
Kingowl, I was pleasantly surprised when you cast the Dispel, and even more thrilled when you rolled a 22. But as I am still learning many rules, especially regarding magic, I noticed you only added +3 to the roll. I did some rule-scouring on the internet and I think you should also add your proficiency bonus. Which would boost it a little higher. Double-check that, please. I am sure a 22 succeeds, but in the future that extra bit might make a difference.