New cards! New good cards even!
Let's start with the least exciting.
Prey Upon is fine but as people have already mentioned we have
Rabid Bite and I'd rather pay the +1 mana to keep my own guy alive and well. At least until I can look through the pool and find some creature that actually want to die. If there are any we will be in business.
Wailing Ghoul is lovely. Yes we already have
Screeching Skaab who serves literally the same purpose (which actually worries me vis-a-vis actually getting the Ghoul) but I personally think this is better. 1/3 is that little bit harder to reach with removal and it can actually block early game aggressive creatures without dying. Like it!
Peace of Mind. Yes. Yes! This I like. This I can work with. For me the simple fact that it allows me to get instant speed lifegain is it's most important feature. Being able to buff/trigger junk like
Malakir Familiar,
Bloodbond Vampire and
Serene Steward (or indeed provide an easy transform trigger for
Lone Rider) is just beautiful. I've spent forever trying to hammer that stupid Orzhov lifegain deck into shape and it looks like this set my be what finishes it up.
Tamiyo, Field Researcher. Damn it Jace! Why can't you let anyone else be a mono-blue planeswalker. You suck eggs, let someone else have a shot. Ranting aside jeez this thing is powerful. Mana is probably going to be a bitch but hey that's what we have
Oath of Nissa for. Fun note about her first ability - it's just 'combat damage', not 'combat damage to an opponent' so feel free to slap it on a token and just blindly throw them forward. Blocked or not it's two cards for you. Or target your opponents monsters to dissuade them from attacking/blocking.