It should also be noted that Mark Rosewater hates Day/Night as a mechanic. While the most recent Storm Scale data lists the mechanic as a Six, this data was from a 2022 Blogatog post shortly after the mechanic came out. At a convention in November of last year, Rosewater clearly changed his position some--he stated he believes it is the sixth worst mechanic in the game's long, long history. That is pretty damning, especially when you remember there are 176 keyword abilities and 55 ability words, so he hated Day/Night enough to list it as worse than 225 other mechanics.

Given the timeline of development, I suppose it is possible Day/Night was already in the works for Lorwyn before he changed his mind, but, given the other issues mentioned on this thread, the generally negative view the community has on the mechanic, and Rosewater's personal disdain for it, I would be really, really surprised if it made a return here (or anywhere).

I’ll be honest, I am surprised we are returning to Arcavios so soon. The plane simply has no real depth to it - even if you count the surrounding areas, they did not have enough lore to fill a whole D&D book. Unlike Theros and Ravnica - where the D&D sourcebooks on the subject were cover to cover with rich information and lore from their respective planes, the Strixhaven book provided what little lore existed, and the rest of the book was various other non-lore mechanisms to pad out the page count.

That said, since they are going back, I hope the focus is on Kasmina - a particularly interesting and under-explored character. Her entire schtick was causing trauma to people in an attempt to orchestrate situations where their sparks ignite, trying to build an army of planeswalkers for some future threat.

That is a unique, interesting, and somewhat terrifying story to tell - and one that they have been reluctant to explore (I think that lore is in an art book somewhere - not really a primary lore delivery system). I am disappointed it did not get explored before they scaled back on planeswalkers - I hope it gets explored now, with her trying to figure out how to adjust her plans in the modern planeswalker era.

The Reserve List is not about power in the slightest - there happen to be some powerful cards on it, but that has more to do with bad game design and broken balancing in the early days of design.

Short form, the RL is about rarity - Magic was trying to do something new in creating the trading card genera. At the time, it was unclear if the game component or the collectable component would drive sales. There was no real analog for a game of this nature, but collectable baseball cards had been a thing for a hundred and thirty years at that point. The RL was created to cater to that creator market, essentially hedging their bets that the game might be less popular than the collection value. This was, in hindsight, kind of dumb and we are suffering for it today, but they were in a complete unknown situation and hindsight is 20/20.

Thunder Spirit is a rare card from Antiquities (a set covered by the RL) that had not been reprinted in a white-border set. That means it met the definition for the RL, and therefore was added. There is no other inquiry - nothing about power, nothing about how useful it would be to the game. It meets the set and rarity criteria and therefore is RL.

It is not an additional three mana though - it is three mana you were going to use anyway to play a creature that normally would provide limited immediate value, and suddenly has value you otherwise would not receive unlocked due to a keyword on a different creature and no additional effort.

Take your “additional 3 mana deserves an increase of 3 power” argument to its logical extreme - you are essentially arguing summoning sickness should go away entirely. After all, you are paying three mana for the creature, and thus, under your theory, you should get three power right away.