For example, you can't cast a sorcery with spectacle during an opponent's turn unless another effect allows you to do so, even if that player has lost life this turn
For Yshtola, it came down to a mix of popularity of the character as well as being a spellcaster, her story and character development offered a wide range of abilities and moments to pull from to lead the deck
With all that mana you need something to do with it, and Titania, Gaea Incarnate has an ability built in
The idea of a landscape that remind you of the tropical Easter Island that's been buried in Snow is very stilling
"Japan's Favorite Final Fantasy Game According to NHK's Grand Poll Is Final Fantasy X"
To make things even better, it included some crazy powerful cards for the time like Dragons Fire and Alladdin, Heroic Outlaw a card that was used in every Ruby deck back then (and is still strong in my opinion)