@Enneth : The only Evolving Buildings which have been offered more than once (via repeated Events) are the three different 'old' 2019 Phoenix and Bear buildings, although at least one other past-Event Evolving Building (the 2020 Festive May Tree) is still available as a Level 1 'base' in the Crafting Menu, and for some time before now a number of older Event-sourced Evolving Building 'bases' (now removed) were also similarly available via Crafting, even though neither the May Tree nor any previous Craftable Evolving Building 'bases' were accompanied by any Craftable or otherwise in-game obtainable Artifacts (and so could not be evolved unless one already had previous Event-sourced Artifacts for them stored in Inventory).
It's not impossible, therefore, that the Wise Golem Level 1 'base' might, likewise, be added to the Crafting Menu (or may even already be in the rotation, but invisible to me because I have the building placed in my City), but even if so, it's not likely that its Artifacts would
also be provided by any in-game method, since Artifacts for Evolving Buildings have never appeared in Crafting or anywhere else in-game outside of their respective Events.
The 'old' Phoenix Artifacts (as well as Artifacts for Stonehenge, the Evolving Building from the 2019 Summer Solstice Event, which was not repeated this year) were put on sale in 'packs' of three Artifacts for £75 on Black Friday/Cyber Monday 2019, and it's also true that all three 'old' Bear bases plus 'packs' of their Artifacts (and Moon Bear Artifacts as well) are currently being offered for sale, for the first time, to players (? some or all) who place and fully evolve this year's Moon Bear, but no other Evolving Building or its Artifacts have, so far, been offered for cash sale in this way. Of course, this may change in future, but that would just be speculation on my part.
As for
why the Phoenix/Bear buildings,
and their necessary Artifacts, have been offered more than once via the Event route, this is probably because - while all Evolving Buildings have various advantages depending upon your playstyle and level of advancement - the 2019 Fire Phoenix and Brown Bear in particular have largely been considered, since their release, to be the most powerful Combat-boosting buildings in the game, with many players regarding them as virtually essential for Combat-focused and/or competitive players. This is probably why these two specific buildings have been treated differently, albeit with their 'old/original' Artifacts being available only via time-limited and randomly appearing Crafting Recipes which consume two 'new' Artifacts for each 'old' Artifact the player wishes to gain. No 'Artifact conversion' system for any other Evolving Buildings has yet been seen.
In fact, it seems likely that the very wide appeal of the Fire Phoenix and Brown Bear - as well as the now-greater appeal of the Tournament time-shortening Polar Bear (due to the new Tournament system) - is also the reason why the Spring/Easter (Phoenix) and Autumn Zodiac (Bear) Events
themselves have been repeated at all, since other Events now appear to be one-offs in terms of their themes, unlike the Phoenix/Zodiac Events, so far.
I am not sufficiently advanced in-game to know whether the Wise Golem offers a particularly good amount of Mana per square, but even if it does, there are other (originally Event-only) non-Evolving Buildings which do offer Mana at known-good rates, available year-round via Crafting and often also via Fellowship Adventures - so it's likely that you will be able to replace the Golem with other, probably comparable (or perhaps even superior?) Mana-producing buildings quite soon, whether or not the Wise Golem may be offered again at some future point.
Hope this helps...
