Some cards have leaked out online, not sure how to link to them but there's some neat looking stuff so far. Maybe someone that knows how can link some stuff into the thread?
The Haunt of Hightower 4BB
Legendary Creature - Vampire 3/3
Flying,
lifelink When The Haunt of Hightower attacks, defending player discards a card.
Whenever a card is put into an opponent's graveyard from anywhere, put a +1/+1 counter on The Haunt of Hightower.
Light the Stage 2R
Sorcery
Spectacle R.
Exile the top two cards of your library. Until the end of your next turn, you may play those cards.
Growth Spiral GU
Instant
Draw a card. You may put a land card from your hand onto the battlefield.
Rakdos Firewheeler BBRR
Creature -
Human Rogue 4/3
When Rakdos Firewheeler enters the battlefield, it deals 2 damage to target opponent and 2 damage to up to one target creature or planeswalker.
Simic Ascnedancy GU
Enchantment
1GU: Put a +1/+1 counter on target creature you control.
Whenever one or more +1/+1 counters are put on a creature you control, put that many growth counters on Simic Ascendancy.
At the beginning of your upkeep, if Simic Ascendancy has twenty or more growth counters on it, you win the game.
Reprints for
Mortify & the rest of the shockland cycle.