Not to be left out, black's Obsessive Pursuit trades quest counters for clue tokens and is a solid card in it's own right
It doesn't matter if Green Goblin was on the battlefield at the time the cards were discarded
Illusionist's Bracers will trigger, copying that untap ability, and you can use the copy to untap a tapped mana source instead
The Ring also tempts you, but it's a mechanic that, in my opinion, does not do much in a multiplayer game
With that said, the Detective classification of cards in that deck really puts in the work as well
While it isnt ideal to play this enchantment without getting another card back, it pulls its own weight well enough that its not impossible for it to be a good play