Maybe I totally got this wrong and my question is obsolete, dunno: When my first targeted creature dies and I have to select another one but there is none, not on my field nor on the opponent's, what happens then?
Good question. As of right now, if no creature can be targeted, the curse does not happen at all past its first targeting. I would like to add a little penalty on for not using the curse to its full potential. Any suggestions are welcome.
I think this could be working out: You can (maybe even always?) target yourself as well insead of just targeting creatures. When you apply the curse to yourself, the curse ends (or doesn't even start but inflicts the full negative effects) and you get a specific amount of damage - for each charge not used 10 damage for example, or you lose a certain amount of (random) quanta/suffer from a mini Black Hole (1 or 2 instead of 3/each). The damage version includes a possible synergy with SoSac.
Being able to inflict the curse on oneself in the first place would also open the opportunity for not being forced to discard with a full hand but pay for the empty slot. Might be useful if a Sundial or Hourglass can be activated but the hand is already clogged.
By the way: The damage-version is quite interesting imo considered the next patch taking effect and SoSac being reduced to only last for one turn. The curse, with 3 charges, would heal 30 hp according to my proposal from above.