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
This matters especially for Lorcana, because the full-bleed artwork design leaves almost no visual margin for error
While these cards come with acorn stamps, preventing their use without rule zero conversations, they demand high prices regardless due to their sheer collectability
Second, we didn't have the resources to playtest all these new mechanics like we would a normal set, so sticking toward known things makes it easier for play design (technically then development) to wrap their mind around it
You create a 2/2 black Zombie creature token for each creature sacrificed this way
The additional combat phase happens immediately after the first combat phase