Alistair, the Brigadier Finally, a nice payoff for casting historic spells, and without once-per-turn restrictions
Skrelv, Defector Mite provides color-specific hexproof as protection or enables poisoning your opponent to death
Older cards are a little more interesting, as they are the closest thing we in the old school community have to foils
Its second chapter is especially nasty, making all your opponents noncreature spells cost 2 more until your next turn
The nice thing is you don't even need to build a full Princess deck for that to be good
My personal favourite of this is Rafiki, Ethereal Guide and Tigger, In The Crows Nest, for their fantastic expressions