"We've got a bunch of priests and wizards here, don't we? Couldn't we just make a new ford, or even a bridge where the river is thinner? Then they wouldn't be able to stop us from going across, and nobody has to be at risk."

"I don't like the loss of tempo it would cause to put a few days to that, especially not if someone's in the process of reinforcing them, but it's definitely a good thought."

"How wide a river are we talking here? I might be able to make a bridge, but I'm not enough of an engineer to do a big one, especially since the paper isn't going to hold up in the water and it has to all be above."

"A little over a thousand feet, at Villareth's ford, but it was chosen in the first place because the river gets wider and shallower there. I expect we could find somewhere half the distance without going too far out of the way, but I'm not sure about a third."

"Iffy. I can try it on dry land by way of a test but it'd be pretty visually obvious, a five hundred foot paper bridge, and give the game away to any spying demons."

She thinks about that for about half a minute, then nods decisively.

"No, I think that's worth the risk. Even if you can do it, it's not like we'd have to follow through, so we'll just have to keep a close eye on wherever you're testing it out for spies. And even if it doesn't come in handy at the river, there's a good chance it'll let us avoid problems at the Leper's Mile canyons - even just having the option to cross in places might free us up a lot. Is there anything we can do to make it more likely to succeed?"

"I'm going to be concentrating on the paper, so someone else'll need to be on the spy-spotting... also I'm not sure how to measure five hundred feet without a river in front of me."

"We can have someone standing by with Silent Image. Your average first circle wizard can get a good 450 feet or so out of it, so it should be good to eyeball things."

"Sounds like a plan, I'll start experimenting with smaller models while a test site is chosen and cleared."

Excellent, then she can go about scheduling patrols to clear a space of demons for that afternoon without being close enough to the crusade that it gets seen. (it might seem counterproductive to do something they're hiding during the day time, but the dark makes demons better at hiding by more than it helps them and night ambushes are way more dangerous if they notice.) 

At which point there's an group for her to ride out with! It's a perfectly ordinary patrol, other than the fact that the soldiers with her are a mix of paladins and their most eagle eyed marksmen and there's a first circle wizard along for the trip. Just another scouting trip, nothing out of the ordinary to see here.

All right. Bridge. Biiiiig bridge that can't touch the ground in the middle because there will be water there.

But you know what? Welexi flies on wings of light. Paper's not very substantial, but it is a substance, unlike light, which isn't at all. She can do this.

She buries paper screws in the ground at her starting point, deep as her range allows, lots of them, anchoring the bridge, and then she starts to walk into the air, domain-sensing the bridge as it forms under her feet, feeling out how to make it rely as much as possible on compression strength and tensile and not demand shear. Step, step, step. Higher up along the arch as it comes into existence.

There's an illusory block right over there now, she need to be able to get another sixty or so feet past it.

(The wizard in question is busy being impressed. It's not that it's unprecedented per se, it's more that the main instances of casually conjuring a bridge out of magic you hear about are to cross the most famous gap on Golarion - he's sure there are a plenty of other examples of it, but somehow none of them are coming to mind.)

The bridge's iffiest moment is not when she first reaches its high point, but when she's nearly to the far end; she winds up doubling back to the beginning, attaching fat paper chains to the underside of the bridge there, and making their ends follow her to the far side, so she can lash the bridge to itself under the arch, make it that last sixty feet, and finally anchor the far end.

Once that's done she wants to shore it up a bit so they can make sure the horses and whatnot won't be too much for it, but the bridge is made.

And then they can ride some horses across it.

Huh, it really does seem to be holding up, even though it's just paper. Her magic really is something! How much is it bending under the weight, can they bring a whole group of cavalry at once or are they going to need to go one group at a time?

She runs alongside the horses and - thinks probably they should go single-file but continuously should be okay.

That'll limit things, but you could still get hundred horse across in only a few minutes - significantly better than swimming. Will she or it need to be defended more than usual?

Well obviously it's a problem if someone sets it on fire.

Right, so focus on any Brimoraks and have an aqueous orb or two handy, they can do that.

Two days later, the army arrives back at the Sellen for the first time since Kenabres. Their approach must not have been perfectly subtle, because there are some demons clearly in position on the other side, but not as many as they had been expecting at the ford. The archers deploy themselves up against the river, their arrows ready to provide fire support, but they make sure to spread out enough that they're not begging for a fireball.

The second bridge comes together faster than the first because it's more execution than experimentation, but it will still take a while.

Fireball.

A number of the demons present are Brimorak, and their flame magic is both extremely long range and very useful against most structures even if they aren't literally paper.

They can prevent half of those, but three of the beads get through to slam into the bridge and detonate an an explosion of flame. It's not enough to do more than lightly singe Kybele through a resist fire, and the spell seems to work just fine for protecting her gear, but several areas in the bridge are now burning merrily.

She can smother those spots with more paper, but she has to concentrate on them one at a time.