I've gone through the Lagdou Ruins on a few of my different playthroughs. I usually play through the Tower of Valni at least 2 to 3 times before starting the Lagdou Ruins, mostly for EXP and gold. It's not exactly necessary, but I'd highly recommend it just so you can get some extra levels. They always help. Ismaire is, in my opinion, the only one of the Tower of Valni characters that is worth getting, but even then, she's pretty fragile. From there, I'd personally recommend purchasing 2 or 3 weapons of your choice (though I'd recommend steel or higher) per-character (or the magical equivalent). Yes, it's over-packing, but it's better to be safe. Likewise, if you've managed to get through most of the game already, you probably have a decent amount of gold saved up. If not, you can either get more from the Lagdou Ruins or from random skirmishes. If you're okay with using the Enemy Control Glitch to your advantage, both Luna and Eclipse are good tomes to have against just about anything. To deal with the Draco Zombies, you're actually not in a bad place, since you made Moulder a Bishop. If you can manage to get your hands on a Purge tome, the "slayer" skill Bishops use will come in handy. I've found it's easy to weaken Draco Zombies with Moulder first, then to let Innes or Neimi fire a couple arrows into them. Draco Zombies are counted as flying units, meaning that a well-trained archer can absolutely annihilate them. I also occasionally use Eclipse to bring them down to half-health and then finish them off with whatever I've got. From there, it's just a matter of usual Fire Emblem gameplay. Keep a close eye on the weapon triangle and always check to see if enemy monsters have Shadowshot. If most of your units are dodging attacks, keep your powerhouses towards the back and just slowly move up as a group. As usual, going too far forward here isn't going to do you any favors. You sound like you're in pretty good shape otherwise! Good luck and have fun! If you were able to tackle the Tower of Valni without issue, you should be fine here. If not, try doing it at least once as a warm-up. Trust me, it's worth it.