You can take Var and ANY thermo together. It all depends on your goals for a specific cycle. First, you have to figure out what the point of taking each substance is, and how to maximize your entire routine to reach your goals.
You do not want to take T-Rex on an empty stomach unless you enjoy puking all morning. You should eat it with a banana or other light carb source.
If you are trying to gain muscle, maybe T-Rex and Var aren't the best together - I would choose Cardio Breeze to help give boosts throughout the day and to maximize energy for workouts. Glucorell-R would be used with carb meals during this part.
Then, after cycle, use T-Rex to help cut the fat to show the muscle gained during the cycle. I would also use Glucorell-R and Yohim ES during this phase too.
But this is just a hypothetical situation based off what *I* would do. You would have to figure out your goals for this situation.