Anima was actually really tough. I had no idea what I wanted her to do. I mean, in game, she's really powerful and that was really about it. Her special attack, Pain, simply did magical damage. And Oblivion was nothing special. So instead of making the card's abilities based on aeon's abilities, I made the card with only the names of Anima's special attacks, Pain and Oblivion in mind and tried to make what I think "Pain" and "Oblivion" would be in Magic the Gathering.
Pain was pretty simple. Just damage, right? I mean, that's painful. but in-game, it was magical damage as opposed to physical, so I made it be -X/-X and put Anima in black. As for what Oblivion would do....a Gatherer search told me that things with the word 'oblivion' in its name in Magic tended to remove or destroy things. The latter fit in well with the Pain ability and then I remembered that black liked to remove cards from graveyards so a few lines of text and a romp through Gatherer looking for wording precedents later I came up with what I think is a pretty awesome card with inherent synergy.
All intrinsic Magic the Gathering game concepts are copyright Wizards of the Coast. Artwork, characters, names are copyright SquareEnix.