Unlikely he knew it,
However the effect is not to 'land a dragon' thats more of a side effect. The real effect is to make a dragon experience the feeling of mortality. A dragons body is mortal technically their soul is not, what would that do to a dragonborn?

yeah, Karstaag was epic. Died 3 times. One of them- I lasted probably about 30 seconds. Wanted that from Miraak.

Nothing. Dragonborns aren't immortal.

Your soul is that of a dragon.

I'm fairly sure that its purpose was to make alduin land, as he would not otherwise. The shout is incomprehensable to dragons because its meaning is mortality. So I don't believe it makes them feel mortal. Until you know, they die and you eat their soul.
And your probably right about Miraak not knowing it. I remembered that the three heroes created the shout, which was after the time of Miraak I believe, or at least on a different continent for sure.

The Karstaag battle was very tough. He never killed me once, though, and I'm on master. He almost melted my 360, though. He summoned up around 4-6 icewraiths at the same time I summoned up a couple of gargoyles (VL form at the time), and my 360 froze solid. The second time I got annoyed by his antics and I killed him.

The Ebony Warrior was tough, but each time I died, it was from mysteriously falling over and getting one-shotted after I Fus Ro Dah'd my opponent. Really weird.

This grants you certain abilities, but it does not make the passing of time irrelevant to you as it is to the Dov. Paarthurnax still addresses you as Joor (Mortal) and Tiber Septim died of old age.

Karstaag was by far more difficult than the Ebony Warrior on master. At least you got something worthwhile from Karstaag. The EW fight gives you absolutely nothing of value. Unless you soul trap him and take home a trophy

From what I understand your soul 'behaves' like a dragon soul hence my thought.

I found karstaag rather easy although I used his summon once just for viewing and forgot to load lol. only 3 summons of him left until his power fades oh well

Nothing sense he's mortal and already understands mortality.

The only way he'd know it is if Hermaeus Mora taught it too him sense the dragon war was way after his time on Nirn.

He was a dragonpriest of the dragon cult. He may have been around at the time of the creation of the dragonrend shout (He might even be the origin of the dragonrend shout, since he turned against the dragons).

Considering that he was defeated by the dragons (his temple burned) he was most likely not there at the time of the uprising (he might have been, but i get the feeling that it happened before the uprising), but we dont know exactly when the dragonrend shout was created, only that alduin hade never heard of it at the time of the uprising. (Considering that a dragon cannot know the shout, it dosent seem to unlikely Miraak was involved in its creation).

not for my battleaxe nord, kartstagg was alot harder because his blizzard drained my precious stamina and his giant attack both staggered and nearly killed me every time...not to mention the dam ice wraiths
ebony warrior was a cakewalk because he doesn't attack until I hit him so I hit him with power attacks over and over until he was dead...he didn't even have a chance

I don't think so. When i fought Miraak he actually said something along this: I was going to join Hakon and the others against Alduin, but i chose a different path.

So its confirmed then...Miraak is your shadow.