Sadly, Starz hasn't shared the Da Vinci's Demons season 3 trailer which was shown at NYCC on Saturday, but they have uploaded a video of the whole panel to the Starz website.
In the third season, Leonardo's knowledge is a curse rather than a blessing. His pursuit of knowledge up to this point has led to disaster, and it will lead to disaster for those around him.
No-body is safe in season 3.
Da Vinci has to out-Da Vinci himself in season 3.
@Tas517 has shared some amazing photos of the cast at NYCC over the weekend, including the one posted above.