The way back to the Abandoned Keep from the Bandit Camp shouldn’t be much of a mystery, but the directions will still be provided, just in case:
Northwest to reach landmark: Ruined Watchtower
When you arrive, be sure to rest before actually entering the area if you’re the least bit fatigued. The first fight in this area will be by far the most difficult, and if you can emerge victorious, you can always exit to rest up.
Battle: Giant Flytrap
As soon as you enter the area you’ll be forced into a fight with the Nymph’s Giant Flytrap. This aggressive plant was a death sentence against your lone protagonist, but facing it with your entire party… well, it’s not much better, honestly. It’s got a high enough Attack bonus to hit most of your warriors over half the time it attacks (assuming your best Armor Class is around the mid-twenties) and it attacks frequently and hits hard, dealing 15-20 damage per hit. On top of that, its got plenty of HP and a decent Armor Class, and to add insult to injury, your entire party will start out surrounding it. This might seem like a good thing, and flanking the beast won’t be difficult, but at the same time you’ll want to move your archers and casters out of the way quick-like, hopefully only enduring one attack of opportunity. Afterwards, immediately buff your party with Haste and Prayer and hope for the best - winning this battle could take a few tries and a bit of luck.
Alternatively, you can try running northwest to the keep’s gate immediately upon spawning, veering to the northeast at the gate and placing your hopes on the [Mobility 20] check to jump the gap. If you succeed, you can heal (the Giant Flytrap will certainly manage a few Attacks of Opportunity given its absurd attack range) and buff up, save your game, then return over the gap to engage the beast on your terms. The outcome of the fight when this strategy was applied was considerably more favorable than simply fighting it at the beginning of the area.
Battle: Owlbear, Young Hydra, Manticore
With your buffs still hopefully active, heal up and then make your way into the keep to confront the Owlbear, Young Hydra and Ferocious Manticore. There’s no reason why, with careful luring, you can’t end up fighting these critters one at a time. Just be wary of navigating your party through the gate, as the game likes to register movement assignments to the top of the wall above the gate, rather than on the ground under the gate. Of these foes, the Owlbear is likely the most dangerous, but nothing a fully buffed party can’t handle, and certainly nothing compared to the Giant Flytrap.
Battle: Redcaps on the Wall
After that, work your way up to the walls and kill the three Redcaps there, including the one on the northeastern walls that harassed you during your escape. The Entangle trap is still in effect, so you’d be well served by luring the Redcap away from that trap before engaging.
Defeat the third Redcap and you’ll be done with this area. Unfortunately there’s no hidden treasure to be had, and the Guardian of the Bloom doesn’t deign to show herself, so you’ll have to be satisfied with the petty revenge you gained by killing her creatures. It’s not all a waste, though, as these fights should have earned you just shy of 1,000 experience, hopefully putting you perilously close to hitting level six.
Continuing the Expedition
When you exit the Abandoned Keep, check the "Kingdom" tab on the map screen. Events will be moving along soon enough in your capital, things that you’d do well not to ignore. If you have the event card "Troll Invasion", you know it’s time to head back to Tuskdale to deal with it. You have a good bit of time to handle this matter, but if you let it linger for around a month or so, you’ll start losing kingdom stats. While not a massive hit to these stats considering it gives you a month of time before penalizing you, it’s something to keep in mind. This will be covered in the section "Troll Invasion" (and following sections), after which you’ll be exploring the southern Narlmarches to discover and deal with this event… and get some extra exploration out of the way.
If the "Troll Invasion" event card hasn’t appeared yet, good news! You have more time to explore, if you wish. Anything that gets you richer and closer to level six is an undertaking worth considering, especially before you get embroiled in this chapter’s main struggle. It’s hard to over-estimate how much stronger your party (especially the good party) can become at level six, as it’s when Octavia will finally hit 5th level as a Wizard, and hence gain access to those juicy 3rd level spells.
If you have a protagonist Wizard, you’ve been playing the game on easy mode for the duration of this chapter, but every party stands to gain. Once your dedicated warriors (Amiri and Valerie) hit 6th level their Base Attack Bonus will likewise hit +6, at which point they’ll gain a second attack per round, albeit at an Attack bonus five points lower than their first attack. Still, this extra offensive output will put your warriors in another league of power, and if further buffed with Haste they could be belting out three attacks per round. It’s not a stretch by any means to say that some encounters which were party wipes before will become speed bumps to your party.
Enough selling. If you have the opportunity and desire to explore further, consider hitting the following areas, and after every day rolls over on your calendar, check the "Events" tab under your "Kingdom" menu and assign leaders to deal with whatever comes up. Head back to Tuskdale when the event card "Troll Invasion" is available.