Due to a rules change that takes effect with this release (see below for details), a Saga that somehow loses all of its chapter abilities will not be sacrificed as a state-based action
If you didn't, the ability won't trigger at all
Celes was considered for Final Fantasy 6, as the set revolves around the World of Ruin, of which she is the clear focus rather than Terra, while Yuna was also considered for Final Fantasy 10
Although Emert's transformed Hades form does cause further cards to be exiled instead of getting re-used again in the graveyard, there are plenty of ways to avoid the downside while still reaping the rewards
It continues to be a legendary artifact
If you want to understand how they compare to other Lorcana card types, check out our guide to Disney Lorcana rarity symbols