Card advantage is so important, that drawing two for free isn't just powerful, it's outright broken, leading Pot of Greed to be banned in the real card game
The combination of card draw, creating a token and the pervasiveness of wizards in Magic adds a lot here
Multiple numbers don't add enough strategic gameplay to overcome the brain freeze concern so as a general rule threshold mechanics just use a single transformation, most often a single number
Collectors have long speculated that Wizards continue to combine Japan e-Series sets into a single English release in an effort to release as many cards as possible before the expiration of their license, but I personally havent found any primary evidence either supporting or refuting this claim (but let me know in the comments if youve found something I missed!) Released four months apart, Ive often thought of Skyridge and Aquapolis as sister sets and perhaps the best way to examine the unique elements of Skyridge is to compare the set to predecessor
Notably, most modern booster packs include a Rare card and two equally collectible Reverse Holofoils (unless one is replaced by a higher rarity card)