Aside: Most of what we say here can be extrapolated to three-for-ones, four-for-ones, and so on
This card wants to help you empty your opponents library with its replacement effect and activated ability
Get twenty Lore before your opponent to win the game
If it helps, think of Items and Characters as similar (Game changing, multiple use), and Actions and Songs as similar (one-use, instant, discarded immediately after use)
Glacierwood Siege I suspect many players will play Glacierwood Siege to get more Crucible of Worlds action going on, but this card can be a strong mill option as well
Its the perfect card to end this article on one that is going to do a lot of work for you in decks that care about keywords, like Odric and Kathril, in decks that care about delirium and Tarmogoyfs (think Disa!), and will also be a great option for late game or midrange decks that just want a nice incidental blocker