What do you think of this as a card in a possible future "life matters" set?

It would be a stretch of the color pie for sure.

Do you think it would be ok for the sake of a set theme or still too much of a stretch? It's realy very hard to make blue interact with life in any way.

Yeah, blue doesn't have life in its pie.

Obviously, you can do anything you like. Wizards did a similar stretch by having an opponent make a choice - either you got to do something out of colour' or something else that is solidly in colour.

So maybe something like "Counter target spell an opponent controls, unless they allow you to gain 10 life"?

Giving an opponent life in exchange for removing their stuff is more green or white, than blue.

So you think something like Book Burning? Nice idea, I think I'm going to think more in that direction. Thanks for that! :)