Ho'kay, time to try to lay out a suggested course of action. I'll just start laying out ideas in a variety of formats.
Alexander: He's a lost cause to bring up this turn, although next turn we have to to avoid losing him. Between the Mage Knight and the awake Archer with the Armor Slayer weapon, he's not going to be blocking anyone any time soon with any sort of dependability at least. There's no helping him this turn except to reset his counter or soak an attack, plain and simple.
Olison, Salvatore, Tantallos, and Valor all have full counters, they can stand to wait a turn. Salvatore is low priority, he's relatively easy to get at, isn't blocking any path, has full counters, and pretty much any enemy can reach him if needed. Healing him is pretty much a waste of medicine/magic right now. Olison is off in the distance, similarly not blocking any path with full counters, but at least he won't immediately go down if brought back up. Tantallos and Valor are blocking paths however, as well as easy access to them but sadly both by enemies and allies.
Derick is in a precarious position, he's the one who we're most likely to lose if we aren't careful. He'll go down with a simple swat, so we just need to gear ourselves for a counter resetting with him.
The first order of business will be killing those three behind the lines, second closing said hole in the lines, and third stabilizing anyone who needs it.
Unless I'm not mistaken, effective weapons have their base damage tripled, not their total, yes? If so, I recommend Charlotte twanging the Wyvern Knight to death. She only needs to hit once to be done with that. Her position isn't really that necessary as long as we have someone who's on their feet behind Derick. Charlotte could alternatively go after the Mage Knight, having just enough range to hit him twice, but the only way to kill him would be a crit with her steel longbow and I'm not particularly fond of the idea of relying on a crit to survive.
The Bishop and the Paladin are easy prey. Raquel first hits the Paladin with her Thunder spell, not the killer lightning, the thunder. Why is to take advantage of both her higher accuracy with the Thunder spell and she is to move to where she can take advantage of her personal skill that grands additional accuracy, along with Riven's charisma for the most accuracy we can pump outta this. I very, very highly suggest she moves to 14.7, as to block off the hole in the wall. Riven tackles the Bishop, not much to tell about this really. Riven just needs to use her most accurate spell, Flux, and she'll deal exactly the amount needed to kill the Bishop. She has type advantage, so she should be fine.
Edwin has two choices here, he can get as close as possible and attempt to sleep the Mage Knight with a 69 percent chance of it working, or sleep a Paladin with an assured sleeping. While getting the Mage Knight out of business will greatly help us, I don't put my stock in gambling, so I suggest the a Paladin to put one out of the fight. The Pillager won't reach the house till next turn, we got time.
Next, we need Seyena to do something. Seyena needs to trade Riven and snag her Concoction, then she needs to trade it to Gregor, then she needs to bring Tantallos back. (Hurrah for trade being a free action, huh? It probably won't be after this shenanigan.)
After that, I suggest Ami moving where the Paladin was, and heal Tantallos to full. Tantallos can't die, else all hell breaks lose. With this, we've almost sufficiently bolstered our wall.
I next suggest Gregor to use one of the two charges of his Concoction to bring Alexander up. He's going down right away, no doubt about that, but this is albaltive armor and it will reset his counter. It should also help keep Gregor alive enough so that he can use the concoction next on Derick.
With the above, we should be okay, I think. I may of overlooked something or of been entirely vague considering this was all from train of thought. Also kinda hinges on effective weapons multiplying the base, instead of the total, but I'm pretty sure it multiplies the base.
Also, I only thought of the enemy turn ahead, so yeah. It will need to be a healing frenzy after this, to make sure everyone else gets back up, this is primarily a 'hold the line' idea of tactics.
EDIT: Also, may be a good idea to double check pretty much everything I said. I may of gotten confused on a part here or there, or maybe thought it was Raquel who had the concoction when it was Riven, or vice versa.