Worldwake introduced Jace, the Mind Sculptor, not only one of the most powerful planeswalkers ever made, but also the first to feature four loyalty abilities
More specifically, vehicles that do nothing other than act as efficiently-sized creatures are extremely bad
Doing the Aftermath Every Magic set is full of new cards and abilities to discoverand Amonkhet brings a bounty of exciting new riches to try
Theres an abundance of ways for you to untap Szeras and sacrifice a few creatures in the same turn to generate a ton of mana since its an artifact, but those creatures need to have cost a lot in the first place
As a quick related aside, theres a common anti-Reserved List argument that most of these cards will hold their value even though a reprint because even if they print more Underground Seas, they arent going to print any more Beta Underground Seas
The solution to this problem was to add a rider to the first ability