You don't choose targets for Miasma Demon's last ability at the time it triggers
Despite that, the rules will still be treating them as the exact same card: Eleven, the Mage and Cecily, Haunted Mage are seen as the same game piece as far as "name a card" effects like Pithing Needle or Runed Halo go, and both
I think from a pure perspective of power balancing and card quality, no card should have this power for just a single mana in Modern
I feel like Isshin, Two Heavens as One might be the better attack + slug/drain/burn Commander, and I think for the hoops to jump through and suboptimal cards it requires, Far Fortune is more of a flavor pick than a power pick
Once again, this is Deathtouch
As noted earlier, the cards weren't initially perceived as collectibles