I'm not sure what this would cost, but it seems a potentially simple version of "destroy target land without setting the controller back on mana as much", whilst punishing people for playing too-fancy lands.

A few points:

• I don't know what it should cost
• if either player sacrifices the land in response, the exchange doesn't happen
• it punishes powerful lands a lot. That's probably ok if it's niche, not if it's maindeckable
• it obviously combos with lands that are only useful to you, but I can't think of anything very abusive.
• the risk is that it's too good at punishing people's mana development by giving them a mountain instead of their only plains or only island. How likely is that? Should limited play support or discourage playing the bare minimum of splash lands?

This:Craterize::Switcheroo:Mind Control. I think its power level is fine.

This looks fairly fine to me as well, maybe boost to if you are worried too much about tempo.
This also made me think about the guy jumping the claim and "Miner 4.9er" kinda stuck in my head

Three mana seems right to me as it is basically a Vedalken Plotter without body.

Oops, totally missed Vedalken Plotter, thank you! Then yes, this must be fine, possibly overcosted.