Incubate is an ability that could appear on any card type, and will always be written with a number so, Incubate N. When an effect or ability tells you to Incubate, you create a colorless artifact token named Incubator, and put a number of +1/+1 counters on it equal to the Incubate number
Your mulligan decisions will also be very different depending on what type of deck you're playing with and against
Finally, copies of Storm itself arent cast either
Contents: 30 Edge of Eternities Play Boosters
Spell Mastery: Spell Mastery rewards you if you have at least two instant and/or sorcery cards in your graveyard, offering a smaller, more easily achieved upgrade than Threshold but still a nod to conditional enhancements based on your graveyard
Verdant Command in Modern Horizons 2 was the most recent, and before that was Ouphe Vandals back in Fifth Dawn