Interesting. I could see him playing well to a deck that relies of Ghostly Prison/Propaganda effects.

That's interesting. I would have guessed the first reply would be someone complaining about how landfall decks might be able to abuse him. Although the idea with prison decks is really interesting actually. I mean it's academic eventually, but that's actually a cool idea to make sure your opponents certainly won't be attacking any time soon after you play him.

I don't think this would see much play in a Landfall deck because those tend to lean more toward Jund with things like the Gitrog Monster.

But this is an interesting concept. Could serve as another Fall of Thran-type card.

Oh I know. I had a jund landfall deck before it become dune-brood landfall. I run the frog there as well, and also am pretty happy with adding white as well as armageddon like effects are a surprisingly handy inclusion in it. And landfall cards like Emeria Sheperd and Admonition Angel or even Sun Titan, who can cause landfall to trigger in the first place, do a lot of work. And that all works nicely with the usual all-stars of landfall, like the big frog, angry Omnath or Titania. Also adding white had the neat benefit of Knight of th Reliquary getting a slot, who also works nice. I'm not saying that this will overcome Jund and I didn't design Thyrrn for any specific deck to begin with.
Edit because you mentioned it; Fall of the Thran also made it in the deck^^