From IPL Caster AskJoshy:

Terran: aoe spine crawler, transforming factory unit, Goliath substitute online

Zerg: burrow moveable blank, reverse dark swarm, detection changes

Protoss: mineral shields, new nexus defensive ability, and............ Cloning?

More concrete details after doors open.

EDIT: Doors are open now. The aoe spine crawler is a Shredder. It costs 150/150 and comes from the factory. It does nothing in its mobile form, but when you plant it in the ground making it stationary, it fires a quick aoe pulse in a visible, kind of large radius. The hitch is, if friendly units are standing near it, it won't fire the pulse. It has to be alone. Good for map control, and blocking expansions maybe.

The transforming unit is the hellion. I only got to see it a little but it basically just flips into a firebat sort of thing and fires in a different pattern, more like a cone than a line. It's slower in its firebat form, as it's walking around.

Goliath substitute is the Warhound, also from the factory. Shoots rockets at air kind of like a thor, but no/weaker splash and actually a really weak base attack. Its ground to ground attack looks like it's firing a tazer at its enemy. Decently quick fire rate, good for support I think, not viable to mass them.

Burrow moveable banelings. That is all.

Reverse dark swarm is just disruption web from the corsair, you guys were right. It's fired from the new "Viper" unit. This unit can also cast a spell to make any unit a detector. Overseers are out of the game. Viper's last spell is 100 energy (out of 200) and it pulls any unit from range to itself, like Scorpion's "Get over here!" or a chameleon tongue. I did it on an ultralisk and laughed.

Protoss mineral shields come from a new flying raider unit. It coats enemy minerals in little white bubbles/shields that must be attacked down or time expired. My SCVs freaked out when Artosis did it to me, so my marines came and cleaned up the shield things.

The new nexus defensive ability seems to be decent for super early game, not much else. Basically you can cast it on any of your structures and it gives it a weak attack. Artosis built a pylon in my mineral line and cast the new spell on it. My SCVs killed it and it only managed to take one SCV to 5 health. Not sure if this will be changed.

Cloning? Looks like another unit, the replicant, can also transform itself like a shapeshifter into an enemy unit that it gets in melee range with. Artosis cloned my shredder, warhound, and an SCV and began building a command center with it.

There's more stuff in the demo, but I only got to play one round and observe the Zerg stuff after my session was over.

OH and the destructible rocks are actually a new thing. There are rocks that you can attack to CLOSE paths called collapsible rocks. This really confused me at first, I thought it was a bug, but it's a defensive measure you can choose to use.