If you would look at this blackboard.

Here is the central chamber of the temple, and the entrance to the nexus.

This is underground. Far enough so, that the only paths through the hard stone are the natural volcanic passageways.

This represents the main passageway. On a normal trip, travelling by foot, this would take you about two bells. Vehicles would be able to make it substantially faster, using the trolley system.

The entrance to the tunnels and the trolleyway, however, are substantially reinforced.

The air army remnants have built barracades, trenches, and we believe also mined the area.

A frontal assault would be long, drawn out, and would likely involve us sieging it for days. We've released careful leaks to make them believe this is what our plan is.

The fleet has substantial siege vessels in it, to also appear as if we are planning a prolonged siege on the entrance.

A problem with this idea, though, is we have reason to believe from communication with the monks who escaped that they have two reinforced points along the main tunnel.

Vehicles, even if they somehow made it past the initial blockade, would have two more blockades to go through.

The bulk of their forces would be at these two points, as the intermediate chambers have also been fortified.

We would be unable to siege these from our ships, as these are in the tunnels, and we would need to move tanks in to break through their positions.

Any frontal assault here would be drawn out, and I could also believe they would trap the passageways, choosing to trap themselves in rather than give it up.

We aren't sure how much explosives they have, so we can't assess how likely they would be to cave in the passageways. We have driller machines to also keep the narrative up we plan a frontal assault.

Their positions seem highly defensible, however...

Escaped monks have let us know of two passageways, that go directly to the main building, and the outside of the Nexus itself.

The air army likely has knowledge these passageways exist, but it seems they do not know where the passages are. These tunnels are how the monks that HAVE escaped have gotten out.

There's a catch. These passageways both are on active volcanic lines.

Both passageways have deadly high temperatures... for anyone not a fire tribe lagre, with a fire aura.