You can equip it up really cheaply and start sacrificing Treasures or Maps to remove pesky blockers
Then since Ur-Dragon is now Skithiryx pumped up by +6/+0 when it was Moltensteel Dragon, you can swing with Skithiryx as a 10/6 to deal 10 infect to your opponent, which causes them to lose the game
At a six ink cost, its one of the riskiest listed here, but played wisely, will yield great results.
While he does have to use your own mana, this effect is still absurdly powerful and can deny opponents the strategic cards they need, while setting up less advantageous cards to be their next draw
Furthermore, both sides of the card are also good protection against high mana value cards and removal
The bookworm has been a Disney icon since the animated film debuted in 1991, so it's not shocking to see her Enchanted card come in at such a high value