Boast ties a large part of your creatures value into attacking, which feels like a relieving de-escalation from an environment where most playable cards get their value on ETB (or even earlier in the case of adventures!) Even more interesting, the range of payoffs for boast are extremely open-ended, including all sorts of utility effects and other incentives not normally associated with attacking
If you do, it is destroyed during the End Phase
Sazh Katzroy was one of the few exceptions to that rule
Like most Magic: The Gathering cards, the value of Xanathar, Guild Kingpin depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Adventures in the Forgotten Realms Promos)
Hes a little less effective than Breeches since he has no evasion, but hes still a solid source of card theft
This is a digital download of the full Princess Twilight Sparkle My Little Pony Commander deck