Devourer/Pest is balanced
Reasons (taken together)
1)In solo (Mono Darkness) or supported (Devtal/Devtosis), the user pays a cost comparable with the effect generated.
2)Each Pest causes a net quanta advantage of 2 per turn. It costs roughly double the cost of a creature with half the net quanta advantage (Ray of Light).
3)It has a variety of counters ranging from CC to anti QD (quanta denial). These counters are not limited to 1 genre.
4)It has not warped the metagame.
The wise words of Sequoia bring yet another restless soul to bliss.
Just in case blueberrymania doesn't get it (not calling you dumb, just checking to see if you are aware of terminology):
1) Basically, the cost of playing a Devourer (or multiple) is reasonable compared to what it does.
2) Pests create a difference of 2 quanta per turn (1
for you, and -1 of something for your opponent), and has twice as much cost as Brimstone Eater, which only creates a difference of 1 quanta per turn (better example than the one by OldTrees).
3) It has many counters, including (but not limited to) simply killing it or using sanctuaries.
4) It isn't being used in almost every deck, forcing people to prepare for it.