CuriousHeartless's speculation sounded fun.
• a white card with the rules text “draw three cards”
A punishing card sounds right, like
Mangara, the Diplomat.
• a red sorcery that you can have as many copies in your deck as you want
I'd expect this to scale with itself somehow, like every other
Relentless Rats card does.
• a futureshifted card (appearing for the first time in a premier set other than Future Sight)
Note that he specifies "premier set" (aka standard set). That means stuff like
Tarmogoyf is still on the table.
• an MDFC with the same card type on both sides that hasn’t been printed before
I'm guessing planeswalker.
• a cycle of enemy dual lands finishing off a ten-card cycle
Based on
this page, the options are... MIR's slow-fetches, ODY's signet lands, BFZ's tango lands, SOI's reveal lands, or AKH's bicycle lands.
I would be surprised to see cycling come back so soon. The slow-fetches and signet lands don't 100% fit with modern land design. The other two are likely but kinda boring. My favorite would be signet lands, honestly.
• “Whenever a permanent entering the battlefield causes a triggered ability to trigger”
This is interesting in that it A) counts all triggers, not just yours, and B) is a trigger itself, not a replacement effect like we've seen with
Panharmonicon and friends. I'm excited to find out what it does!
• “Pests, Bats, Insects, Snakes, and Spiders”
Sounds like a goth biologist to me. Perfect for Witherbloom.
• “Each mode must target a different player.”
Huh, this sounds cool.
• “where X is the number of cards in your library”
Reminds me of
Invincible Hymn. Maybe it's a planeswalker ult, because that is often a large X.
And finally, here are some creature type lines from the set:
• Creature – Turtle Druid
Turtlefolk!
• Creature – Bird Warlock
More warlocks! Also aven!
• Creature – Frog Wizard
Frogfolk! Wow, they are really diving into new animal races in this set. I love it!
• Creature – Eye Bat
Wha...
• Legendary Creature – Dryad Druid
Say that one ten times fast.
Okay, that was mostly commentary rather than speculation, but I still had fun.