On normal mode? Well, when I was aiming for a low turn count, I had Shanna rescue Roy, canto'd away towards the secret shop, (She had Maltet equipped and therefore could OHKO any wyvern in her path) and moved downwards with everyone else. After turn 3, I'd visited the Secret shop and was running away to the sieze point-I also deployed Merlinus so I could send lots of Boots to him. I then made use of the boots and got Fir to the boss ASAP, defeated Murdock and siezed in...I think it was eight turns. Total. Anyways, you don't wanna turtle this map out in my opinion-You need to act as if you're on a time limit, since you don't wanna deal with more wyverns. To deal with the ones that are unavoidable, Berserkers can go onto peaks and utterly decimate them, Bows can make pretty short work, (albeit probably only steel bows and more powerful ones) the legendary weapons deal a ton of damage, and a Wyrmslayer in the hands of a swordmaster is an easy ORKO for the most part. Watch out once you get near the sieze point, because there are obnoxious ambush spawns there that potentially can do a lot. Bring Physic staves, use Warp to speed up your bosskiller if you need to, (Durandal or the Armorslayer are your best bets, the latter being the ideal option.) and get out quickly.
What is an archetype you'd like to see absent in the next FE.