Yesterday, MTGSalvation user Trollcreature posted some information about Theros in the Speculation section of Rumor Mill that was initially ignored, but then proven to be credible. Among the info: Some of the card text of the legendary Sphinx creature Medomai, confirmation on the Nimbus Maze cycle, and the apparent presence of Thoughtseize. Now we have clarification on these and other points, since much of the content of the posts was ambiguous.
On Medomai, Trollcreature said "and from the last I heard (months ago) Medomai is U/W and was 5cc" - this has wavered between converted mana cost five and six since this was posted, but the correct text appears to be:
Medomai the Ageless 4WU
Legendary Creature - Sphinx (Mythic)
Whenever Medomai the Ageless deals combat damage to a player, take an extra turn after this one.
(Medomai the Ageless can't attack during extra turns?)\
So instead of having a cost or checking for a condition, Medomai instead functions rather like Lighthouse Chronologist, which is interesting.
On the creature-exiling one-mana white enchantment: "But to clarify the enchantment swords. it should read close to W enchantment. sac~ remove target non-enchantment creature from the game, its controller gains life = to power. May also just be creature and non-enchantment creature."
This may not be true - it seems the one-mana enchantment he refers to is actually Chained to the Rocks, which Mark Rosewater mentioned, and that looks like this:
Chained to the Rocks W
Enchantment - Aura (Uncommon)
Enchant (creature? enchantment?) you control
When Chained to the Rocks enters the battlefield, exile target creature an opponent controls until Chained to the Rocks leaves the battlefield.
On Thoughtseize: "I heard it was in the middle set of the block." This means if it does not appear in Theros, we need only wait until Born of the Gods for confirmation.
On land cycles: "The new lands are a cycle total of 10, with 5 in Theros, and the other 5 between Born of the Gods and Journy Into Nyx. There is a very similar land with these in functionality: H____ D____"
The "H____ D____" comment appears to refer to Halimar Depths - which is curious, since Nimbus Maze has little in common with that card. Perhaps this means there will be another land cycle, at least one of which has an ability that can scry in some way.
Further confirming the return of scry, Trollcreature also said that Magma Jet would be reprinted.