It does not trigger if you are attacking a planeswalker a player controls, but not that player
Mardu Pyromancer relies on its graveyard to cast Bedlam Reveler and sometimes Gurmag Angler and uses it as a value engine with Faithless Looting, Kolaghan's Command, and Lingering Souls
If you had a ticket to the event and queued up at the Lorcana booth, you could purchase a Booster Box and Starter Deck for The First Chapter
The two decks varied in their specific choice of disruption suites, with Musasabi opting for more traditional countermagic over This Town Aint Big Enough, but the core is the same
Then when they do you can exile and then cast it with any mana, not just their color - great stuff for the winning
If youre winning, its got menace and trample