Ibex also suffers from a generally worse power boost for this kind of effect. Overrun effects want large numbers of creatures - if two creatures are getting +5/+5, that is ten extra damage; if ten are, that is fifty damage.

Ibex depends on you having both a wide deck and a big anchor creature to buff everyone - that is a bit awkward, and essentially means you need Ibex and another high cost creature to get value. Behemoth only requires you to go wide - you get the power boost based on what the card already wants to be doing, without another companion piece required.

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.