After spending the evening experimenting, I have found the following:
Draw All League Cards does not trigger a ban. (As of yet)
4x Battle Speed does not trigger a ban. (As of yet)
Evolve cost -40% does not trigger a ban. (As of yet)
VIP 4 does not trigger a ban. (As of yet)
Reward Multiplier: 5 does not trigger a ban for MOST things. However, if you use this during Journey, you will be INSTANTLY banned after completing a fight.
Using unlimited currency mod seems to trigger a ban almost instantly. May be delayed, however.
Gems "spent" in game do not seem to trigger a ban - that is, gems that the game believes you to have earned, NOT the unlimited gems cheat.
During this evening, I completed many quests which awarded gems (Which were multiplied by 5) and spent them on 10x Foxies for a guaranteed Legendary as well as some Epic and Rare cards to add to my line-up.
I also got VERY lucky, because I was completing the current event in-game which awards event sparks (Which were also multiplied by 5) and I was able to use them multiple times. On one of these, I landed on 525x Gems, which was also multiplied by 5. I then bought another 10x Foxie.
The only thing that triggered an automatic ban from all of my evening's activities was doing Journey with Reward Multiplier: 5 active.
Hopefully this helps someone! Play safe, everyone!
