I really like this design space. The Old God strategy can really lock another player out of the game, but if it doesn't quite get there, it would expect to get out-rushed.
Only criticism is that it's slightly ahead of every official Dominion card in making the game tricky to play by hand, since it creates the "duration is not in play, but will still have its effect" effect without requiring a 2 card interaction to invoke. Every other case of that requires the duration and a non-duration effect to combine to make it possible. It's considered a "gray sin" in the game's current game philosophy, there are some ways it might happen, but it's not super too likely. (MtG has lots of game design "grey sins", like the confusion of +1/+1 and -1/-1 counters in the same game. No card in a serious set is allowed to produce both kinds of counters, but it's permissible for them to have a small chance to run into eachother.)
It's hard to think of good solutions that wouldn't damage the nice design here, though. It might be one of those cases where the best answer is to break the soft rule because the design is otherwise so cool.
