Speaking of stocklands and Kyren Toy, is there any reason this land isn't using a similar mechanic? Seems like cleaner way of getting the same end result, plus you now have interaction with all the spells/abilities that add or remove counters, and add a measure of risk to saving up.
I had intended there to be a benefit to using the mana ability even if you get Wastelanded. The Toy template doesn't allow for that.
T2 Show and Tell is already pretty easy, isn't it? Ancient Tomb and City of Traitors provide double colorless without having to be your first drop. I do think that ETBT is necessary to balance this (and honestly might still be too strong), but I'm more worried about Standard than Legacy. This card is pretty much the single most efficient mana battery ever printed. I don't think that matters so much to formats with lots of strong acceleration already, but when you've got a smaller cardpool available, I could see it becoming an issue.
Good point. Still, better to have only 8 ways to get turn two

just from lands than 12. I don't usually think of the Standard context because I don't play Standard. I'm generally trying to hit the sweet spot of 'Vintage playable', which at times means 'too good for Standard'.
Side note: This rocks hard for Shops. Was that intended?
Actually I was thinking of this as a way to break out of Stax locks. Play this (when it ETB Untapped), activate it under Trinisphere. It dies to Wasteland. Repeat. Play Island (or a dual, etc.) and have

available to break out. Unfortunately most of the things that are good against Stax are good in Shops. With ETBT this land does less for escaping a lock than a Spirit Guide would in most cases. Too bad.