as someone who not only Mains Vordr but also beat the conquest line for them and got the achievement I think I can give a reasonable review on this DLC.
Pros:
Versatility. this clan not only has 3 war chiefs you can switch between depending on the need for a minor lore cost, but the branches used to place your lore into action can be moved around as well for half it's original cost. a good example is the lore that mines resources for you. not only does this stack with any miners you have on the field, but it can be destroyed and replaced in a new tile with resources to mine.
Excellent Support Class:The Owl is arguably one of if not the best support class in the game. they can start off with 3 scouts without upgrading any buildings, and with a Norn (scout) on ally town halls you can become favorable with them and use your lore in their spaces (you can help mine resources for them even). and if Owl has access to at least one wheat field then they can become a powerful food economy for trading.
Norns Norns Norns: Arguably one of the best scout alterations in the game. capable of collecting lore from neutral resources, help improve relations with neutral factions and they can annoy your friends.
THE RELIC: Realm of Myrkviðr has to be one of the most busted relics in the game in my personal opinion (especially if used correctly). the ability to terraform the land to where every upgraded tile you own has Forest and Deer on it, and any body of water has Fish. with this relic you basically never have to worry about Lore Production or Happiness ever again. frankly the Relic is the only way Owl Clan really gets a functional late-game economy. without it Owl would be a mid-tier clan. and in a situation where you have a teammate this relic becomes even better. if you can convince your teammate to trade you some of their land, you can not only upgrade their land practically for tree, but put extra wood production and a whole new food tile for them, in a single tile. doing this multiple times and giving the land back to them would ensure your teammate never has to worry about wood or food ever again. (sorry for gushing on about this relic, I just really like it from an economic standpoint.)
Cons:
Vegans:The Owl clan do not eat deer or fish, instead tiles with deer and fish provide happiness to the hippies. This is all well and good until RNG decides you have no wheat tiles nearby you. Thankfully there is a lore that allows you to make a tile fertile fields so you don't go hungry, but in personal experience you need at least 2 wheat fields in the mid-game or you won't scale with the rest of the clans.
Tree Huggers: The Tree Hugging hippies don't cut down trees for wood, instead they use the trees/world tree to grow their houses from the roots. to do this they need Lore. so instead of wood you get +2 lore from forests (this is why the relic is so good btw, because trees produce lore naturally for you.) That being said the early game can be a slow rev-up having to switch between Lore and Building since both are the same resource. this also means without wood you are automatically unable to trade in the Bonfire. so some events you miss out on.
Big Tree:I love the guardian of the realm and he is a nice tanky addition to any army. the problem is the unique victory condition the guardian has is very difficult to pull off, especially in a duel. with teammates backing up the tree it's possible, but even on those situations of large scale combat the tree is ultimately useless. too slow to chase most target and only hitting at a bit weaker then the Jotann the big tree is just a damage sponge in most situations, and not even a good one as most players will ignore it to take out your damage dealing units instead of the lumbering mass of bark.
Subpar Military:Aside from the big tree your war chiefs are also just alright. One of the war chiefs is made specifically for combat and they still feel less significant then a normal war chief. with two subpar hero options it forces you to be more reliant on the little guys like axe throwers and champions. this of course means your army needs to hit hard but is also very squishy outside of the tree. Personally I think Owl is best suited for the support role, even in combat. I see Owl as a secondary add-on to whatever main military ally you have. as for Duels? God speed.
Conclusion:Owl Clan is a refreshing take on the game play, fun to play and manage, great support/scouting option when used right. However it's also very reliant on Map RNG working in it's favor and has a lackluster military that usually needs assistance in a real fight. Overall I want to give it an 8/10 because I really enjoy the clan (I do main it afterall). but I feel like a 7/10 is a more reasonably rating.
If on sale definitely get it, it's a refreshing take on this great RTS game.