vague idea.

Just as a note, the Redemption ability doesn't work on lands for the same reason flash doesn't work on lands. You don't ever cast a land, you play it from your hand in a specific action. I like the mana ability though.

Also, I am of the mind that: a) exiling is a bit to rare of an occurrence for this ability to really be that useful or easily understood for someone glancing at it, b) I am of the opinion that exiled stuff should be really hard to get back, and those effects should be few and far between.

It certainly would work. This is a very tentative thing that I have no certainty of putting in this or the next set, so I merely didn't remember/bother to adjust the reminder text to say "play" instead of "cast".

Also it looks like you didn't look through the set, which specifically involves Delve and exile triggers as a theme, and cards like ((C25228)) that exile your own lands. We're not talking cards that exile themselves as a cost here, but rather the kind of effects we might expect on a conspire card. But then again, it's a very tentative concept, hence why I didn't actually put any more in the set, and the card itself is not even active in the cardfile.

Oddly enough, the effect (on nonland cards, anyway) has only limited interest for constructed in that very often, the cards with the same CMC will be other copies of the same card, unless you try to break it by granting flashback, but that seems unnecessarily tortuous.