Vis is the western orc leader and Ostro is the eastern leader, just like the Goths. Vis has lost his cave system to the party.
Ostro thought Vis would get himself killed defending his caves, but decided to use diplomacy. At first glance, Vis failed but Ostro can't turn out Vis's tribe, he'll need the manpower to stop the party. Ostro had the smaller of the two colonies so his position was initially weaker but the characters cleared the Cave B rather quickly so everyone is sweating and swearing.
If the characters had hit them and left the cave system, Vis would still be in control and Ostro could think of making a move on him. But the dastardly humans know where Ostro's den is and could take him out. Oddly, they don't know where the exterior cave mouth is, so they have not tried a direct attack. The party also lacks the manpower to defend their position in cave B while hitting the cave mouth anyway. They discovered that when they took the cave and most of the orcs simply fled to Ostro's cave C.
Vis and Ostro are unwilling compatriots. They are currently acting as co-leaders who work as a pair, but what is really happening is each is hoping the other gets an arrow in the eye.
The orcs are getting smarter and wiser when it comes to tactics. The orcs woefully lack missile weapons and the party showed them what a sling is. They are now trying to make their own slings, which is far easier to make than a bow or crossbow. This has put the wounded warriors in the position formerly held by women and the women in the role of warriors.
The other thing the tricksy party did was set up triplines. But instead of using rope, they gathered up rocks from around the caves and made 6-12 inch high steps in random places. Because the orcs see by infrared, they can't see a difference between the cave floor and the low rock piles. Rocks from the same environment have the same temperature.
My daughter thought this one up from reading Les Misérables. The barricades in Paris were made in this fashion by ripping up the cobblestone streets to make a low step then placing all kinds of crap on top of it. If you managed to punch a hole in the barricade, you ended up stumbling into the muck that was under the cobbles. While revolutionaries rained gunfire and pots of boiling water down on you.
They also put up a wicker door over the cave entrance which creates the problem where the orcs can see through it but not well enough to tell how many people are in there. Or more importantly, if the dogs are there. The party has taken to howling, which creeps out the orcs.
The next trap they came up with was to place candles in the dark with cloaks and ropes hanging in front of them. It looks like movement, so the orcs rushed in to attack. The party hit them from behind, from spaces that were kept dark. With missile fire. It's not very deadly, but the orcs fight their way out of a brighter area to a darker area while under fire. Usually, if they can flee, they do flee.
The orcs are now lighting everything up in their caves because it's easier to deal with than sudden shifts in lighting. They are copying the wicker like door screens and steps to foil attackers.
The net trap that caught Solvo was spread down the hall from room 13 at about knee level. It makes movement really difficult. They added rocks and garbage below the net to make noise and cause twisted ankles. The orcs haven't countered this as they don't have enough oil to set it on fire. But that is their plan.It's interesting that the kiddos are using history against me, I'm a social studies and history major. Should Vis and/or Ostro survive, they will be the trickiest villains ever. The siege of cave B is really changing the Caves in unexpected ways.
I can't wait to see what happens next.