What's interesting about these new spells is how they seem to merge together two "branches" of the Witch Doctor's skill sets.
For example, take a look at this new monstrosity:
It looks like a combination of D2's Inferno with a summon spell...what are those creatures in the flame? Bats? Is Blizzard making a Starcraft joke?
Another curious skill. It seems that our friend has the uncanny ability to summon poison dart frogs that either do damage by proximity, or automatically explode, doing disease damage (which we can infer from the green appearance of the target). If these are indeed suicide minions, then I'm reminded of Starcraft again! This time with Starcraft 2 - the Zerg "Baneling" unit (a suicide unit that explodes when it gets close to an enemy, splashing everything around it with corrosive acid).
I'm particularly interested by the fact that these skills seem to automatically veer towards one elemental skill - frogs tend to be naturally poisonous, bats tend to revolve around fire. Maybe Mongrels are unique in the respect that they can be empowered by either poison of fire?