23rd Slate, 305
Lokum went outside to the battlements, accompanied by a small group of the fort's finer artisans. The hover-orcs loitered on the other side of the river, waiting for the dwarves to make a deadly mistake. "These hover-orcs can avoid any proximity sensing device we know to build by simply hovering above the pressure plates and triggers. That rules out conventional traps or plate-based designs. They are also unnervingly fast," Lokum paused and directed the dwarves' attention to a moving orc. The air flow in his wake caused a small stack of polished rabbit bones to topple. "so their speed rules out any corridor-based design where we trap them in transit. We must, instead, tackle them while they're standing still, or confined to a small area."
"We could build some catapults to pelt them with stones." said one of the miners.
Lokum considered that for a moment and said "That could work for some of the orcs, but the corners won't be covered, and our workers would have a very hard time working outside while the orcs are so close."
A marksdwarf overheard the conversation and pitched in. "We could use some more bolts, y'know. We got nothing, not even bones, because the orcs are sitting on them."
"Hovering above them." one of the junior marksdwarves corrected.
"We don't have a lot of bone inside our walls, but we do have some copper. You'll get some copper bolts, but don't get used to it. We don't have a lot of land, which means we won't have a lot of metal." Lokum noted down his promise. "Let's get back to the traps. We can't waste ten bars of metal on every siege. What can we do to a loitering hover-orc?"
A novice mason shyly blurted out the elementary answer "Magma?"
"Well, that could work, but we can't build magma pipelines above the tundra while the hover-orcs are there." Lokum said, feeling a little sorry for shooting down the mason.
"We could build the magma pipeline inside and lure the orcs in." the mason added.
Lokum smiled and patted him on the back. "Now we're talking! We could build two magma pipes near the northern entrance, and add two flooding rooms below them. But how will we get the orcs inside?"
A miner pointed at a a freshly killed rabbit, surrounded by feasting hover-orcs. "We could tie up some of our animals as bait."
"Yes, that could work." Lokum paused to think. "Well, I have all the ideas I need! You'll get your work orders shortly. Meeting adjourned."
14th Hematite, 305
"The hover-orcs are gone! They lifted the siege!" one marksdwarf shouted from the battlements. He and his colleagues have been bothering the orcs with copper and bone bolts while the miners, masons and mechanics worked on Lokum's trap, codenamed Magma Shower. The digging was nearly done.
16th Hematite, 305
"The hover-orcs are back!" that same marksdwarf shouted.
"Big deal. Use the bone bolts we've been making to convince them to leave." Lokum didn't have time for that petty business. He was now in the final phase of construction, installing and linking the moving parts.
26th Galena, 306
"Why are people dying?"
"I don't know!"
"Are we sealed?"
"Yeah, I think so."
"Lokum's dead too. What the fuck?"
"I don't know, I told you!"
"They don't have any archers outside, what the hell is going on?"