Aragorn shakes his head.  "I never trained with the bow."

He's several times wished he did, but when he was young, the Elves were all so much better than him that he didn't have the dedication to get really good at it.

"And your plan...  It would work if they didn't know the Ring was here.  With it...  it might work."  He holds up his hand in salute.  "We will be in the hollow down there when you return, most likely.  Good luck."

The only alternative is to run away and abandon these people to their fate. Gord isn't exactly decided on risking his life for their sake, but putting down a bunch of wraiths is risking one's life for the sake of everyone in the world.

Nondetection. He doesn't think it will help but now's not the time to be stingy with resources. Disguise self, in case some of the wraiths get away and bear a grudge. And he takes off running downhill; he doesn't have time to be maximally stealthy all the way and he's hoping they can't actually see him while he's far enough away, horses or no horses.

Can he approach them stealthily to where it'd take him five minutes to close the distance running, without them seeming to notice, while actually being in a tearing hurry?

Well, how far does he want to go out of his way?

If he sets out down the side of the hill where the hobbits and Strider came up, he'll quickly find a hidden path leading back towards the front face of the hill (toward the Road where the... six wraiths, now... are sitting on their horses) some of the way down.

But only some of the way.  By about halfway down, he'll be more in the open with only bushes for cover.

Gord needs to get to them while it's daylight. 

He can go invisible for eight minutes but he doesn't know if it will help; Golarion wraiths can sense living creatures nearby. The invisibility could also work for a getaway, if he needs one later and can get out of their live-creature-sensing range.

...if they can fly faster than he can run, and his channels don't work and they end up chasing him, then he's fucked. But channels only harm undead, so he doesn't have to check if they're really wraiths before using them, and it really ought to be enough. He could just approach them openly and then channel at the last moment, but they might ride away if they see him coming. (He really hopes they can't fly.)

So, he'll try to approach them as stealthily as he can without risking it being dark before he reaches them - if they can only see at a distance using their horses then this might actually work? - and then, if they let him get close enough, cast invisibility and minute buffs and close the rest of the distance.

This isn't a great plan but it's the best one he's got. None of his defensive abilities or resources work against incorporeal undead; turtling up on the hill went out the window the moment wraiths came into play.

The wraiths must have split up while he was on the way down - there're only four of them there before he gets close.

One of them seems to be facing (for what it's worth) in his general direction, but he hasn't moved recently.  In fact, none of them have moved at all, nor have their horses except for the slight wind blowing their cloaks and manes.

So if they have sensed him, they're not giving any signs of it.

If two of them already split off (and where did they go so quickly, the horses surely can't fly) and another three are unaccounted for, then most of them might strike at the hill-top while these four draw him off. 

...but they won't strike until it's dark, and this is still his only chance to take out some of them in relative safety. It wouldn't help anything if he turned back now. (He does check whether Strider is desperately waving for him to come back from the top of the hill.)

So he closes to a few minutes' running distance, ducks into the best cover he can find at that range - some bushes that might at least obscure his casting - and casts invisibility, protection from evil, remove fear, and runs towards them at a slight angle, as if to pass them from the right. 

Do they track his movement, or do anything else?

They might not see him... but the Ringwraiths can smell a Man running toward them.  He doesn't smell like a Ranger, or one of the natives of Bree, but he's most likely a Man.

A moment after he starts running, the closest wraith shrieks a piercing cry, one that they know will put fear into the hearts of all but the bravest of Men or Halflings.

But to their surprise, he keeps running without fear!  Two of the wraiths gallop toward him.

That's a problem; he wants to catch all four of them in a channel.

A dire wolf appears, as large as one of the horses. It stalks towards them with menacingly, growling, not breaking out into a full run so as not to scatter them. Do they turn back?

They... draw rein at the suddenly-appearing wolf.  It doesn't smell like any wolf or warg they've smelled before, but it's pretty clearly a wolf!

One of them circles around, to try to cut off his retreat should he retreat.

The other hisses at the wolf in Black Speech, in case it can understand, with magic to make his words convincing:  "Kill the man!"

Gord's Comprehend is still up so he catches that. Do the wraiths have magic to command beasts, but no detect magic to see that they're summoned ones?

Aaargh, they're so close, the other two wraiths are just a couple of minutes away. He needs to make these ones think he's enough of a threat to make them regroup, or call the others to help them, but if he channels they might just scatter.

Would making them scatter, and only wounding or (at best) downing two wraiths, be a victory? A victory here is making them afraid to attack tonight. Gord will be better prepared tomorrow.

Getting only two of them... doesn't feel like a victory, not one that'd make the other four too frightened to attack during the night.

It's unclear how much good the invisibility is even doing him, at this point. Gord casts Lesser Mirror Image, runs towards the closest rider and tries to hit it with his sword, like the dumbest charge out of stories.

The wolf is going to prevent the other rider (or at least its horse) from interfering with this, or running off.

Summoned beasts?  The Ringwraiths haven't even heard of such a thing.

Not having normal eyes, they don't even notice the mirror image except through their horses.

The wraith Gord is charging pulls out his own sword.  It's invisible to mortal eyes, and half-intangible, but he wills it firm for long enough to parry - and he was a good swordsman in his mortal days.  He'll parry and try to cut Gord off from the wolf as he charges.  He won't stab him back; his sword is no Morgul-knife and would probably evaporate if he tried.

Gord can't see the enemy's sword, but he can tell when his own sword is parried by what at least feels like a metal weapon. If he keeps at it for a few rounds, can he manage to hit the wraith and force it to reconsider?

The wraith not trying to strike back with its invisible (?) ghost-touch sword is weird, but maybe it's fighting very defensively for some reason, or maybe there's no invisible sword and it's some kind of parrying-only spell. Gord tries to hit its leg, on the principle that it ought to be stuck in its stirrup and his greatsword might have better reach than the wraith (presumably) bending down to defend its leg. He can't see the wraith itself, now that he's close enough to notice that, but it's conveniently wearing visible clothes.

If he can't manage it in a few turns, the summon will expire and the other wraith will presumably attack him, at which point he'll have to settle for channeling at these two.

Gord strikes out at the folds of cloak which look like they're hiding a leg.  He feels he hits something - but then when he pulls back his sword, it's smoking and twisting as if he'd stuck it into a very hot fire.  It's still magic, and not quite destroyed yet, but it's still twisting and if it twists much more it will be destroyed.

The wraith can damage magic weapons as a reaction?! 

If he doesn't get them all with the channels, manages to destroy his sword, and the rest come after him when he's unarmed, then he'll shortly be dead. (By his hand, not theirs.) He has a backup holy symbol in his bag (a tiny one), and a backup mundane sword which is going to be approximately useless. And he might have managed through great effort to become enough of an annoyance to these super-wraiths that they'll bother chasing him if he retreats now.

If you can't retreat, advance. 

Gord takes off running towards the two wraiths who stayed behind, in a last-ditch effort to draw all four of them together. If he has to parry with the remains of his sword, well, better it than him.

One of the two wraiths who were fighting him rides after him, but at a slow pace not trying to catch up; the other one stays behind to watch the wolf but follows as soon as it vanishes.

(The wolf just vanished?  Was it a magical warg after all?  But it's not sunrise - and then why didn't it understand his command?)

The other two wraiths turn at Gord's approach but don't otherwise react.

... And as he runs, his sword continues to twist and shrivel to uselessness as a sword.

...he gets out his backup holy-symbol-on-a-string and wounds it tightly about his wrist. Takes his backup greatsword from his bag of holding. Waits until they're all as close together as they'll let him bring them - he'll practically go into melee range again, for this.

Channel. And he watches them carefully, trying to notice any reaction, if that's at all possible when all he can see are billowing cloaks framed on emptiness.

The Ringwraiths screech at this sudden wave of something invisible that hurts like fire would hurt a living man.

They are hurt, not destroyed - but nor are they yet strong enough that they want to keep facing this or someone who could do this!  When he doesn't even have the Ring they are seeking!  Raising their hands and shrieking again, they wheel their horses and gallop away east along the Road away from the setting sun.

Gord's primed to sprint after them. He can't keep up with a galloping horse, not and do anything, but he could probably catch one or two with a second channel.

He has a better plan, though: the pair that's closest to each other gets hit with a Confusion. Plenty of range for that.

Time to see if these wraiths fly when their horses are (temporarily) taken out of action. (He really hopes they take their cloaks with them if they do.) 

The Ringwraiths are solidly bound to their Lord, and strong in their own right; the Confusion passes over them.

But their horses are normal horses - broken to their task by the cruelty of Mordor, but horses of flesh and blood just the same.

The two horses farthest back rear, and buck, and one lashes out at the other's rider -

- and then the one who struck out at a Ringwraith neighs in surprise and terror, and bucks even harder - and his own rider falls off.

(The other two Ringwraiths keep galloping away.)

Gord keeps running towards them, and channels again when he gets close enough. 

Now, do they flee, or do they stand and fight? And how do they flee if they must abandon their horses?

They both screech in pain.

The one who's still horsed tries to master his horse, and - pressing down on its mind as much as he's able through the pain of the fire - manages to at least direct its confused dance away from this strange Man.  He's not moving fast enough though - so if the Man makes any other move he's going to have to abandon the horse.

The one who's unhorsed... strikes out at Gord with another ray of fear.

But when that doesn't do anything, he abandons his cloak to fly away.  Gord feels a wave of weakening chill, and the cloak settles to the Road in peace.

(With Detect Magic, Gord can see a shadowy wraith rushing away northeast, along the ground; nothing is visible with ordinary eyes.  There's no magic in the cloak itself... but there's something inside it that is magical.)

Meanwhile, the horse tries to run, neighs in pain when it finds its leg stiff and weak, and starts hobbling around in confused pain.

Bad news: they can go fully invisible, and move quickly when they do. Strider was right that the horses were just for extra senses; Gord can only hope they'll be unable to attack effectively without them. 

Probably good news: they might not be able to fly after all - that one rushed away along the ground. And they can't take their cloaks with them when they're not riding the horses, which implies... Gord isn't sure what, exactly, but when a fleeing foe leaves a magic item behind, one assumes said magic item was empowering them in some way. (Also, Gord just got some magical loot in exchange for his sword, which he still hopes he can rescue with Make Whole.)

So, on balance, it seems that unhorsing these Riders is a good move, as opposed to something that makes them stop sandbagging and swoop down invisibly behind your back where you won't see them coming (he's checking for it now, but he can't keep checking forever). He should press his advantage as much as he can, while they're still in daylight and in disarray.

In which case: go, summoned cheetah! Catch up with the two that galloped away and do your best to maul at least one of their horses so it can't run away from Gord! The nearer wraith will keep another turn before Gord tries to finish it off for good with a third channel, assuming it doesn't decloak and flee before then.

If you've never seen a cheetah before you might mistake it for a species of leopard. Unusually gracile and lean, with a curiously short head and long legs, but ultimately just another medium-sized cat; not nearly as scary as a tiger or lion, and certainly not dire. No danger at all, to a horse that started galloping away three turns ago.

Until what you thought an ambush predator, lazing about in clear sight and definitely not about to ambush anyone, stands up and stretches its long legs and gives you an innocent look, and suddenly it is next to you before you can flinch away.

It's not magical or supernatural; that would be cheating, and beneath it. It is merely extraordinary, the embodiment of raw speed in graceful gleaming fur; a Medium-sized animal that, once an hour, can outrun Shadowfax for a brief glorious moment, and would give Nahar himself a spirited try.

Cheetahs don't normally hunt horses; their hooves are too dangerous, their bodies too massive. A cheetah that is running for its dinner will look for easier prey.

A summoned cheetah, happy to sacrifice its own existence for a chance to tear or break the leg of a galloping horse? That's a different matter.