Impossibility is its habitat. Kydele, prophet of Kruphix Illustrated by Sam Burley Standard Not Legal Alchemy Not Legal Pioneer Legal Historic Not Legal Modern Legal Brawl Not Legal Legacy Legal Comp
Then search your library for a basic land card, put it onto the battlefield tapped, then shuffle
With Boromir in play, you'll have to pay full price for it, as any "free" spell will be get countered
The best part of this card is that its a Humility effect that only gets your opponents, and it costs 3 mana at instant speed at that
Like Heroic Intervention, you can use it to nullify most sweepers and all single-target removal, but unlike Heroic Intervention, its also capable of protecting yourself from game-ending spells and abilities
Theres also the typical chapter on creating adventures in the setting, as well as a chapter going over the treasures you can expect to find in a campaign set in the sprawling Ravnica cityscape