Severe Knock/Rattle (maybe from transaxle?)

No it does not.

My car has always been at the mark on the dipstick and never ever have seen oil above the throttle body butterfly or anywhere near the maf. That would be a manufacturing nightmare if true.

Now...there's always a little pool of oil at the bottom of the tb. That's because of the Atkinson cycle of this particular motor and causes no harm at all.

Keep the oil at the mark on this car. The bottom end is splash lubricated and will not tolerate a very low oil level for long. We are seeing many a blown motor from poor oil maintenance on this site.,

 

There's been a few reports of clogged cats that caused bogging...lugging...I mention it because of the sulfur smell. Or the knocking will activate the knock sensor and pull timing on the motor making it run like a mutt.

Because of poor performance of the motor it probably ran on hybrid battery real hard and may have overheated that battery producing that smell. Your poor wife probably freaked when she started hearing that knocking and ran like hell to get somewhere safe. Ask her if she heard a loud fan noise or hissing noise in the back seat too. Thats the hybrid battery overheating.
I would give the hybrid battery fan vent a good sniff and see if it stinks. Should not smell at all. if its stinky the battery got a workout.
But it would have thrown the triangle of doom also I would think.

 

This was better than a Sherlock Holmes movie.

 

I wish mine was as simple. Cylinder 1 was bad. Replaced coils . Took to dealer and 1 and 3 are bad now. 4 new coils 4 new spark plugs and back to dealer and they say some antifreeze in cylinder 1. Went on vacation and came back after 1 week. Car seems ok now. No more knocking. But when I got back from dealer it knocked bad...
Thoughts? Is my head really bad? Am I crazy? Is my 2010 with 190k miles just fine.
I have no idea anymore. Spent $1000 all I'm so far on this and I dont know.

Ps the water anti freeze reservoir hisses when I removed it. Did that fix my issue. I assume that is under pressure and is normal

 

Start another thread.

While you're waiting for responses to that.....and BEFORE you drive the car again:
Check your oil for antifreeze, and read the top ten posts under the search heading of "Head gasket" or "EGR"

Good Luck!

 

That sounds pretty much exactly like the story in this article, which I have linked on various similar threads before, and hardly ever manage to find them again, because I keep forgetting the source of the article. AECS. AECS. They make diagnostic scopes, and the article is kind of a plug for how hard this Prius was to diagnose without their scope; the owner sold it at a loss, thinking it was beyond repair, and the problem turned out to be a spark plug. But the interaction between the misfiring engine and the hybrid transaxle sounded just murderous.

 

... in one of the Gen 3 forums as your 2010 is a Gen 3, if the article ChapmanF's article does not solve your issue.