Heartfire Hero, Abuelos Awakening, Hopeless Nightmare, and This Town Aint Big Enough were largely dependent on Standard synergies and have limited appeal elsewhere, destining them for the bulk bins
Your opponent can choose to add one card to their hand for each mulligan you take
The prices fluctuate a lot depending on demand
A 5/7 Inkable character like this is incredibly tanky, while the Witching Hour is such a strong effect letting you and your opponent draw three, discard three, and then punishing your opponent for letting them dare to draw as many cards as you
As both the leader of a Commander deck and as part of the 99, the ramping aspects of the card help players get to big, splashy spells like Craterhoof Behemoth and Rise From the Dark Realms