The "Textless Cosmic Foil" variant of The Mind Stone from the Marvel Super Heroes set has an estimated pull rate of less than 1% in Collector Boosters
Aside from this, there's also the new 'Vanish' attribute, a sort of Achilles' heel mechanic intended to balance out some of the more powerful characters (typically 'Illusion' types)
At the time of Primeval Titans printing, the card Valakut, the Molten Pinnacle already existed
If this spell was cast from your hand, create a 0/1 black Wizard creature token with "Whenever you cast a noncreature spell, this token deals 1 damage to each opponent." Rebound (If you cast this spell from your hand, exile it as it resolves
The Amber/Emerald deck, also known as Dogged and Dynamic, is a nice sampler platter of the expansion's characters and Locations, with a strong go-wide strategy meant to overwhelm your opponent with numbers