None of these numbers are tested. 3 Mana seems like a great spot, the question is how many counters it needs and if the trigger is interesting enough. In any case, its probably cool.

Hm. Yes, this looks cool. Fulfilling 2 other quests would normally be enough to trigger this, though not if they're one- or two-counter quests like Quest for the Gemblades. It'll be annoying when you need to play your land for the turn (getting your landfall quest counters on Khalni Heart Expedition, Zektar Shrine Expedition etc) before you can cast this. But still, I like it.

Where did the alt-BFZ challenge come from?

Just friends chatting with each other about how horridly BFZ turned out. Obviously the quests would be different, and it might actually be unfun when you don't actually sacrifice the quests that require that just so you can accumulate more quest counters which is what I'm most worried about. The numbers honestly don't matter because this isn't supposed to be a fully developed set. Just some guidelines on what an alt BFZ would look like.

Hmm, two copies of this just go infinite. Which isn't the worst thing, but probably is undesired.

Actually, this would work fine with a number of one or two counter quests... assuming you don't sacrifice them. Two copies of Quest for the Gemblades with this on the table could make combat a very tricky proposal.

I don't see the problem with this going infinite. Its not a mandatory loop, nor does it really reward you that much for going infinite.

6 quest counters is a lot, so the loop makes it super easy to get two free planeswalkers, defeating the steep cost