MF Gear Swapping debate

[Mavfin]

How often does it appear though? Cause that was the first time I ever saw it. I was on my way to Leo's Manor when I saw it and was like, "wtf is this place?". I was pleasantly surprised, needless to say.

I've seen it more often than not in that area. It's like any other cave or feature. I think they have X slots to fill of 'features' when it generates the level, and the caves and events each fill one. You just haven't gotten that one drawn for you before.