So, against all odds, I managed to complete Yarne's paralogue on my first go.
First turn involved me picking a fight with both teams for a shitload enemies to tackle (no reinforcements thankfully), and splitting my team in two to handle both teams simultaneously, while sending Panne up to recruit her son and future Mr. Avatar. Frederick and Lissa got iced on the enemy phase (thank god for casual) due to a shitty dodge fail (nailed on a 10% to hit). Avatar rallied spectrum.
Second turn involved me being an idiot and sending Gregor (who is rather behind in levels) paired with my Avatar (who's still fragile as all hell) into the western fray alongside Panne, Olivia, Yarne, and Severa. Que enemy phase that saw Gregor eat it on a bullshit dodge failure early on. Leaving my Avatar all alone to get absolutely swarmed by almost a dozen enemies (including at least one forged Rexcalibur user). Que my Avatar's finest moment as she dodgetanks almost every hit aimed at her (out of the 9+ enemies that took a potshot at her, each with 50~60% odds, only three hit, leaving my Avatar alive at only 2 HP).
Third turn involved my Avatar absolutely surrounded by enemies (out of the 12 available spots surrounding my Avatar, 9 of them were occupied by enemies, 2 by allies, and one by an impassible wall (can't even fly over it)) with only 2 HP to spare. Severa can clear two enemies on the north left side of the clusterfuck, but can't get to the right where a forged Rexcalibur toting Valkyrie is laying in wait, nor can my Avatar move far enough to escape from even the Generals through the northwest. Panne or Olivia can gib one additional enemy on the left side of the clusterfuck but Olivia is too weak to handle anybody but a Sage or the Valkyrie, and Panne can handle anybody but the Valkyrie is too much of a crap shoot to rely upon (needs 2 hits to KO, either Olivia support attacks or the Valk gets a shot off and potentially oneshots my Wyvern Lord); either way they're not enough to punch through the right side of the clusterfuck let alone deal with anybody coming over from the eastern front. My one remaining healer is Cherche who only has a Mend staff at best and is mired in the eastern front along with Virion, Donnel, Chrom, and Gaius. The good news is that she's right next to Chrom and can hit up the convoy for a Physic staff. The bad news is that her magic stat sucks so much she can't even reach my Avatar with the staff let alone heal enough HP to survive anything more than a stray spear. The south is all but blocked by a wall and there are forests everywhere south and to the east of that wall and eat way too much move for anybody to move through....
....save for my Warrior Gaius with his Acrobat skill. He proceeds to charge all the way from the east and directly behind the clusterfuck surrounding my Avatar and proceeds to punch a hole into it, allowing my Avatar an avenue of escape over the forests to the south where none of the Generals, Sages, Paladins, or Valkyries can reach her. Severa and Panne get to work on dismantling the clusterfuck and the match is mostly uneventful thereafter.
By turn four almost everybody is dead save for the bosses who finally start coming after me. The next five turns involve me leading the General boss around in circles while Panne visits every village for loot.
