I can see it now...
The fortress has been empty for years, but nobody on the outside knows. Every year, the elves, dwarves, and humans send trade caravans to Hellcannon. Every year, they fail to return. This is how it has always been, and this is how it will always be. It's become a ritual of sorts for the outsiders. Sacrifice your merchants to Hellcannon, and your crops will grow. The merchants embrace it as a challenge. Each wants to claim that they were the first to survive the trip to Hellcannon.
This year, it's no different. The 494th-annual elven caravan rolls up to the fortress. The ice is everywhere, stained dark red from millions of bloody deaths. The wilddeath watches the merchants, but do not attack. The merchants become excited, for it is believed that the wilddeath is the cause of all the deaths. The wagon pulls into the small entrance and descends into the fortress.
The elves walk along with their goods, looking in awe at the fortress. Everything is a dark shade of red, like the ice outside. They wonder among themselves what attacked the fortress and caused all this gore. It must have taken millions to spill this much blood. It would take nearly 500 years of annual invasions to soak the corridor this thoroughly...
The realization dawns on the elves. This is not the blood of invaders. Rather, it is the blood of the annual merchants, coming to the fortress in hopes of finding riches, but finding their deaths instead. The merchants try to turn and run, but it is too late. The traps have triggered, reducing the elves to a large puddle of blood, slowly soaking into the earth around them.
Deep within Hellcannon, as the last of the elves are liquified by the uncountable traps, a mechanism turns. One pump stack drains a reservoir of magma, while another fills it in a different pattern. A line of 5x3 tanks stretches incomprehensibly to the west. The 3 easternmost tanks are partially filled:
494
And so, the fortress counts its latest victim...
Hellcannon is a curse upon all life. The wilddeath has nothing to do with the deaths of the caravans. In fact, they are the least dangerous thing in the area. The dwarves are what really should be feared. Though they died centuries ago, they are still terrorizing anything that dares enter the fortress. Their corrupted souls haunt the fortress endlessly, taking pleasure in watching the pitiful life forms be reduced to yet another coat of blood in the entrance corridor. Even the demons of the underworld hide from the dwarves. Their monstrous creations know no bounds in their atrocity.
Another year passes. Another caravan arrives. The wilddeath have passed the point of being entertained by the slaughter. It's all just routine now.
495...
A haunting voice rings out from Hell itself. A ghostly dwarf is standing in a patch of strawberries, making a plaintive gesture.
"All according to plan..."