You're down the last badly wounded guy, with 6 PCs to go before it does. While I will make you roll to kill it, the encounter is basically over.
So now would be a good time to start working out your out of combat healing uses, formation for the next fight, whatever.
And it's feedback time.
First of all, this was a level 13 encounter worth 6700 XP - considering the premise of the game, this might be the easiest encounter in the whole thing. I wanted to start with what's basically a standard encounter to see how'd it work out and to see if building a good monster team would have a big impact. The monsters used were as follows:
[sblock=Monsters]Briar Witch Dryad: level 13 elite
2x Dryad: level 9
Shambling Mound: level 9
Stormrage Shambler: level 11 elite
2x Battle Briar: level 14
Feygrove Choker: level 12
[sblock]
Quite frankly, it didn't do as well as I hoped. The Battle Briars were a huge disapointment. In theory, the combination of Difficult Terrain Aura and Threatening Reach should mean that they get lots of OAs and deal a bunch of extra damage. However, IIRC, the only OA from a BB that hit was when it was attacking the other plant - and these monsters had +19 attack. So they seemed more annoying that effective.
The Dryads actually seemed a lot more effective than their level indicated, until you killed them. With the damage bonus for not having more than one enemy nearby and the Briar Witch's aura, they hit really hard. In this (extremely favorable) terrain, they could pick and choose their targets and charge too, for extra accuracy. I wish I had used more of them in this fight, especially since the other locations I have in mind aren't so forested. Taking them out right away was a good choice, since they had low HP and defenses but could hit really hard. Also, they didn't get to do very much attack + Shift to stay out of reach.
The Briar Witch was a mixed bag, IMO. On one hand, saves were about the only thing that the PCs rolled poorly on, so her cages lasted a long time and did a lot of damage. On the other hand, I thought the Curse aura would be more effective.
The Shambling Mound was slow, so it didn't get to double attack until near the end (when the briar witch couldn't help it). It's attack was low, but I figured that 2 attacks would still lead to some hits.
The Stormrage rocked - except when it spent its AP. That aura was nasty, and triggered far more frequently than the damage effect from the BB auras.
The Choker slowed the PCs up, but didn't get to use many of its abilities like Choke or Body Shield.

Erdric's high Perception and the initiative order really messed it, apparently. My initial thoughts figured that more of the PCs would be going earlier, so that more people would have advanced into the middle area. The melee lines would be drawn up there with ranged attackers staying behind. Then the choker could have snuck up and attacked without too much of a melee counterattack. Instead, between the initiative and the choker restraining people, most of the fighting took place in your deployment zone. Against the more densely packed PCs, the choker couldn't really put the squeeze on an isolated target.
Yeah, the plan I came up with several months ago turned out not to have held up so well. Who would have figured?
It seems like monster powers that basically screw people over (save ends) or until end of next turn are pretty common at higher levels. This seems somewhat annoying in an online context, since you don't have an ineffective character for a few minutes while sitting with your friends; you have an ineffective character for like a week, while playing with strangers AND it's difficult to have conversation. I'm not really sure how to deal with this - it seems pretty much the nature of the beast that bad things will happen to characters, especially under these conditions. I try to keep things moving quickly, but still.
As far as the PCs go, I think that Tharos is big star. He did a ton of damage. Unfortunately, some of it was to your team. I haven't worked it out, but I'd estimate that he's in the top three on the monster team as well.
I think you guys got pretty lucky. A bunch of crits. Early on, it seemed like nothing single target missed. Still, you were dishing out a lot more damage than I expected, especially with area stuff. And most of the PCs didn't even spend AP or use dailies.
Consequently, I'm planning on moving each of the later encounters up a level - they still fall under the guidelines for encounter construction and thus should still be fair game.
Note that encounter 2 is pretty much set in terms of monster mix (although I might change some of the levels/numbers), the results of this encounter and the change in level have left me willing to change my plan for the final encounter. I have some ideas of my own for changes, but I'm willing to see if you have any good ideas. So if there's a new monster you want to go against, mention it and I might be able to work it in. If you have something against a repeat monster from this encounter, then say so and it might not show up again. Or maybe I'll put more in to spite you.
