While you can, at this point, go about fighting things, resolving quests and just sort of generally being awesome at the world, which totally can’t take that and buckles before your coolness, you’re still short a party member- a full party is three people, and you’re once again stuck with just Shulk and Reyn. Fortunately, this is easily remedied- by following the plot of the game!
This is the time to head down that last hillside path- for it leads to Tephra Hill and Tephra Cave, where the Mag Mell ruins are. On the way you’ll see a number of Bunnit holding branches with their tails- Wood Bunnit and Hand Bunnit. A bit tougher than their earlier counterparts, they’re still not much of a match for any kind of intelligent fighting. You can also find Evil Rhangrot along this path- a larger and especially nasty Bunnit- but it will pay to hold off for now.
There are a number of areas where you can jump off from the path to a different area below- but don’t give in to temptation. Very few of these places are over water, and the ones that are mean an awfully long swim getting back to Colony 9 (unless you choose to use the Map and Landmarks to quick-transit). Instead, you should head along the path to its end- the entrance to Tephra Cave. Here, two Colony Defence guards wait, making sure that things stay safe for Colony 9. There are also a few quests for inside the cave, which you can get from the guard on the left.
Most importantly, though, Fiona waits for you here- you didn’t really think she was gonna let Shulk and Reyn go off on their own, did you?
Besides, as it turns out, the two forgot to bring the cases needed to carry Ether Cylinders, and she’s been helpful enough to bring those along as well.
With the addition of Fiona to Shulk and Reyn, now you have a full party- and now nobody’s going to be losing out on Skill Points or Affinity Coins by not being part of the pary when battles are won and levels are gained. This means that now is the time to head back to the Colony 9 area and complete all the quests you’ve got, as well as kill all the monsters you intended to.
Very conveniently, you can also take the opportunity on the way back to Colony 9 to kill Evil Rhangrot and meet a number of other ‘kill x of y monster’ quests as well. By this time you’re likely to be almost done filling up your Collection Book for the Colony 9 area as well, and just to make things even better, with all three party members present it gets a lot easier to make sure you’ve got all three characters as well-equipped as you can for the time being.
With a team of DPS-Tank-DPS, you’re very well equipped for dealing with single large monsters or the packs of light monsters that you will find yourself fighting as you go about the harder quests in the area, and you should have a party pushing level 11 or 12 in no time- a good level to head into Tephra Cave at. Take your time and make sure you’ve done everything you intend to though- it would be a pity to have to go back and forth a few extra times, although the Landmark Travel system makes it much less of a pain than it would be in most games.