[Item]Devourer Enchant suggestion
Suggestion: Scaling with monster kills --> scaling with level. It's not as flavorful, but it makes the item much more consistent, providing a healthier play pattern.
Both Feral Flare and the Devourer enchant follow a similar pattern of being (too) powerful when ahead, but not strong enough when behind, especially if the enemy team is warding and taking over the jungle. Generally speaking, snowballing effects, such as + damage/health on minion/monster/champion kill on items, are either too powerful, or simply not worth it. In the case of old warmogs, the base item was strong enough for champions that could reliably farm the stacks, but it was only marginally sub-par on those that couldn't. The stacking items, Mejais, SoO, and Leviathan, have similar, but much more feast/famine, patterns of play in that they are very weak when purchased, but if you can secure kills with them, they become way too powerful for the cost. The items were/are fine, because of the loss of stacks on death, and the unreliability of building and retaining stacks, but it's an unhealthy gameplay pattern of items functioning to get you further ahead without spending more gold. In the case of the devourer enchant and feral flare, this is exaggerated by the items being on par (after the patch slightly below par), at first, but significantly stronger than they should be if you manage to get ahead, with no way for the other team to bring it back down to a more reasonable level. Counterplay through items (rather than in champion abilities or mechanics) is generally unhealthy for the game, but having to change your play because of an item is arguably worse. These two items have the additional effect of promoting ignoring the lanes and farming the jungle, rather than a mix of the two, which conflicts with what some potential junglers that would purchase the item would want to be doing.
TL;DR: Devourer Enchant (and Feral flare) make people that pick them feel pigeon-holed into farming the jungle rather than having a presence on the map, and are inconsistent in performance. Too strong when ahead, not strong enough when behind.