Denial against FGs is tricky to pull off at times. Simply because of the amount of towers, extra quanta, etc you pull off. Although it can be pulled off with the cards you present. You have no way to damage or deck out your opponent but 3 vampires, one you are spawning more but still there is no way you can do enough damage against the FGs. Even a full field (23) meaning you can't deal more than 96 damage a turn. Giving up on your denial. To run the full denial instead your going to be pecking at FGs, and two thirds of the field will be pests. means you will likely be doing at most 24 damage a turn. This means you need an eclipse at least otherwise most of the time you would be running close if not decking out. Also to run denial and have entropy, is pretty obvious to have a discord, not much will disrupt most of the FGs more and it'll add some damage.
So + 1 eclipse, +1 discord minimum. but what to give up? I don't know, it'll lose efficiency.
PVP yea, I see that, low level Arena like bronze, I could see too. FGs, Gold, Plat... those are going to be rougher... At least specify the FGs you beat with it or a 10 game run before claiming that when trying to claim a denial against FGs.