I use Ghost Kill and Sun Move too.
But, I personally choose Ghost Kill because for me it actually suitable for any team I use, I also use Sun Move mostly when I change to Earth main or certain Fire main team
I choose Ghost Kill to focus on mostly because when I mood my ninja, I always choose between the Att+, Nin- or Att-, Nin+
Not a very good mood I know, because I don't feel like decreasing their defense/resistance when its already low. So, Ghost Kill actually helping me increasing whatever minus on that that ninja I use

That's a good point. I'll try that too hopefully it works out for me. thanks ^_^

i used to use Ghost Kill tactics in my early playing. I managed to bring it to level 4 too, but now i use Sun Move.

On long term Ghost Kill tactics is a tactics you can run only if you are a whale, otherwise you absolutely need a more defensive tile.

At level 6 you'll begin to feel the difference between not owning that 990 resistance, because the attack/ninjutsu tiles are useless if you are under chaos/immobile/sleep while defense/resistance/hp tiles are useful even when you are under those statuses.