Bug in star trek to exploit:
When you do the 6 fights for the spar crystals, one slot will light up if you have three fights of the same type, you have to light another one to get a free crystal on the same day. Here we exploit a bug .. You can get an extra crystal even the next day if you can't light two of them in this way: At least one must be turned on, the next day if you open before the start of the day you will see that it will remain lit even at the beginning new day .. Well we already have one slot turned on (even if zero) and other 6 possibilities to turn on the other one (I always manage) turned on the two slots withdrawn the crystal before updating the game.