• The following counter types: bloodline, croak, invitation, judgment, omen, slime, and suspect
-Edgar, Charmed Groom
-Grolnok, the omnivore
-Wedding Announcement
-Faithbound Judge
-Soul Code Tablet
-Toxrill, the Corrosive
-Investigator's Journal
• A new mechanic that removes something never removed before
cleave I guess
• A popular and powerful creature card from an Innistrad set gets reprinted
Thalia, Guardian of Thraben
• A new artifact token, along the lines of Clue, Food and Treasure
Blood
• A card that makes red Dragon Illusion creature tokens with flying and haste
Manaform Hellkite
• A mechanic that first appeared as a faction mechanic returns
Exploit
• A new legendary creature card that combines two characters that previously each had their own legendary creature card
HAL AND ALENA, PARTNERS
• A new card that lets you cast certain cards off the top of your library
Cemetery Illuminator
• A new mechanic which is a mirror of an already existing mechanic
Training
• A legendary character returns, but now as a Vampire
Odric, Blood-Cursed
Next, here are some rules text that will be showing up on cards:

• “Choose a number between 0 and 13.”
By Invitation Only
• “with mana value less than or equal to the number of Vampires you control”
Dominating Vampire
• “If it’s red, you may cast it this turn.”
Chandra, Dressed to Kill
• “Zombies you control have flying.”
Geralf, Visionary Stitcher
• “At the beginning of your upkeep, any opponent may sacrifice a creature.”
Innocent Traveler
• “Kraken, Leviathan, Octopus, or Serpent”
Krothuss, Lord of the Deep
• “twice that many of those tokens are created instead.”
Kaya, Geist Hunter
• “Whenever a Human you control dies,”
Laid to Rest
• “equal to the number of permanents you control that are Spirits and/or enchantments.”
Katilda, Dawnhart Martyr
• “Then if you control exactly thirteen permanents,”
Stensia Uprising
Finally, here are some creature type lines in the set:

• Creature – Human Ranger Werewolf
Oakshade Stalker
• Creature – Angel Soldier
Angelic Quartermaster
• Creature – Zombie Scorpion
Fell Stinger
• Creature – Serpent Egg
Biolume Egg
• Creature – Eye Horror
Revealing Eye
• Legendary Creature – Human Peasant
Old Rutstein
• Legendary Creature – Spirit Warlock
Katilda, Dawnhart Martyr
• Legendary Creature – Slug Horror
Toxrill, the Corrosive
• Legendary Creature – Kraken Horror
Krothuss, Lord of the Deep
• Legendary Creature – Vampire Noble (two new ones)
Olivia, Crimson Bride
Edgar, Charmed Groom

• The following counter types: bloodline, croak, invitation, judgment, omen, slime, and suspect

I expect all of these to be particular to a certain card each, not a theme. Bloodline either for a choose-your-tribe card or specifically a vampire lord; Croak for some big Frog or enchantment with frogs in the art; Invitation counters are are almost definitely flavorfully spreading invitations to the wedding, perhaps an enchantment that puts one each upkeep and if you control a Vampire with a specific power or mv or higher you can pay something and sac the enchantment to gain control of all invitees; Judgement is kinda vague but probably either a human or human flavored; Omen counters prob build up to pay off with some big effect like mass discard or a massive token or maybe even a Rise that takes forever to set up; Slime counters are also placed by Sludge Monster so I assume a Blue Horror that doesn't copy the "a 2/2 with no abilities" clause but some other way to take advantage of them; and Suspect counters I wanna say something to do with investigate, "Whenever X happens put a suspect counter on ~ and investigate. This triggers only once each turn. 4,sacrifice a Clue you control: Tutor something with MV equal to or less than the number of suspect counters on this" maybe.

• A new mechanic that removes something never removed before

Easy guess with "something never removed before" is Emblems but that's a terrible mechanic in a non PWer heavy set and makes no sense for Innistrad. It being a full mechanic does interest and confuse me because a single card in a set could be very flexible but a whole mechanic has to fit set themes.

• A popular and powerful creature card from an Innistrad set gets reprinted

I'm just gonna say Snapcaster and move on.
• A new artifact token, along the lines of Clue, Food and Treasure

Like this is so vague it's hardly worth a real guess. But with the above we get mana, life, and draw so maybe it's something that mills you. Or maybe some sort of "Favor" like wedding favors, not sure what they'd do. Could even like...make an opponent discard (at Sorc speed only of course)

• A card that makes red Dragon Illusion creature tokens with flying and haste

Sounds neat. Hard to guess at the card but I'd guess a big Dragon, like Balefire size. Since it gives them haste I assume it pumps them out when you meet a certain criteria in your main phase and not a like on attack.

• A mechanic that first appeared as a faction mechanic returns

Hard to guess. I kinda want Spectacle or Surveil. They both fit Innistrad well. Hellbent maybe, but they've moved from Hellbent to 'Heckbent' on more modern designs.

• A new legendary creature card that combines two characters that previously each had their own legendary creature card

Hal and Alana. I'm calling it. Hell I called this BEFORE we got this teaser.

• A new card that lets you cast certain cards off the top of your library

IDK, probably not legendary and whatever it lets you cast is related to set. Could be cards with flashback, could be Vampires, could be cards with mana value 2 or less because why not.

• A new mechanic which is a mirror of an already existing mechanic

A lot of possibilities. Like just too many even trying to be Innistrad thematic.

• A legendary character returns, but now as a Vampire

Assuming it is a character that didn't debut in MID, the only possibilities I see are Alena, Geralf, Hal and Thalia. All others are either dead, inhuman, or both. I'd lean Geralf.

• “Choose a number between 0 and 13.”

That's such a big range it's hard to guess but it's probably gonna be worthless outside a kinda fun gimmick.

• “with mana value less than or equal to the number of Vampires you control”

Hmmm either a steal (ETB on a big vampire or AA on an Olivia, I'm guessing AA on a new Olivia) or a recursion card.

• “If it’s red, you may cast it this turn.”

Alright I'm gonna be bold with my guess.

"Whenever you cast a red spell, exile the top card of your library. If it's red, you may cast it this turn."

• “Zombies you control have flying.”

Ehh this is just gonna be some like 5 mana either blue or blue/black signpost uncommon. COULD be on a good Rare but I feel good for limited mediocre for commander uncommon lord.

• “At the beginning of your upkeep, any opponent may sacrifice a creature.”

SOmething flavored as a restless being demanding tribute. Maybe an Enchantment that becomes a huge demon until EOT if they don't sac, but gets a +1/+1 counter if they do. I know Desecration Demon was Ravnican not Innistradi but I'm imagining an Enchantment version.
• “Kraken, Leviathan, Octopus, or Serpent”

Something related to the religion of Lier and/or Runo, I bet. Hopefully it's on an enchantment or a creature of one of those types and not a human.

• “twice that many of those tokens are created instead.”

Presumably something limited. May only affect noncreature tokens?

• “Whenever a Human you control dies,”

I don't know but I want it. Maybe make a 1/1 Spirit?

• “equal to the number of permanents you control that are Spirits and/or enchantments.”

Spirits and Enchantments are a weird overlap, wonder if it points to the Spirit mechanic/theme of Crimson Vow? Hard to guess the overall effect without knowing but may be a mill? Life gain? Self mill and gain life?

• “Then if you control exactly thirteen permanents,”

Not gonna be a game win, they just had a 13 related game win. Maybe a like Wolf that gets an insane number of counters? The "Then" means this is a second or later part of some other effect. Like a Mayael's Aria effect or maybe end of a ramp spell.

• Creature – Human Ranger Werewolf

Ehh. It's a thing, hard to guess on these. There's other Werewolf Rangers too. I'd guess Reach, fights, or both.

• Creature – Angel Soldier

I'd be shocked if there's only one of these. It's again fairly generic.

• Creature – Zombie Scorpion

Probably a common or uncommon filler but I'll be happy to see it. Maybe we can get a deathtoucher that makes you lose 1 and draw 1 somehow on death.

• Creature – Serpent Egg

Either builds counters somehow and makes that many 1/1 snakes on death, counts the number of something on its death and makes that many snakes, or when it dies you make a single X/X snake based on something like the number of creatures in your grave. Either way I'm expecting it to....OH WAIT that says Serpent not Snake! I could've edited all this but I wanted to show my real thoughts. I'm guessing some cheap blue creature iwth like 0/4 stats and it gets closer to hatching as you cast sea monsters, then transforms when you reach a certain point. Sea Monster 'tribal' equivalent to Thing in the Ice and since it'll be inherently worse it'll be cheap.

• Creature – Eye Horror

EYE. Black most likely. Just hard to guess at more for some of these but I'm happy to see it.

• Legendary Creature – Human Peasant

No idea the fitting character but fun to see a legendary peasant. THis is a broad guess I know but I'm gonna say one of hte colors or color pairs in Bant since that's Humans. I'd be happy if he was MonoWhite for my Adeline.
• Legendary Creature – Spirit Warlock

Ehhh, ghost of a witch maybe? WU or UB maybe WB but I'm betting one of the first two. Flying, some sort of storm ability that'll either be annoying or aggressively medium.

• Legendary Creature – Slug Horror

YES. Gitrog gets some friends. I hope it's just called The [Insert location] Monster. Black/Something else. I kinda hope not Green to not JUST be a new Gitrog. Expect posts on r/EDH about wanting to Rule 0 it and Gitrog which will get responses like "Normally I'm all for Rule 0 but does Gitrog really need help?"

• Legendary Creature – Kraken Horror

Lier and Runo's God, I bet. Or at least an aspect of it (I actually forget if they worshipped a God or Gods, if Gods then one of them). C'mon Dimir Sea Monsters.

• Legendary Creature – Vampire Noble (two new ones)

Edgar and Olivia or Runo and Olivia. It's...Olivia's wedding and she's been heavily focused and got a card the previous two Innistrad blocks, she's one of them. The question is if the other is the return of Edgar or if Runo will finally get his card. I'm actually guessing all three will, but one of either Edgar or Runo will be the Precon face. I'm gonna put this guess: Mythic Olivia, Rare Runo, Edgar as face of the Precon