Overgrowth Enchantment Cycle

With the prominence of the mutate keyword in the set, I'm very wary about using the familiar creature aura boosts that tend to win games in limited formats. Combined with a creature with mutate, it's an extra +1/+1 for free. So I would need to lower the power of them, which makes them a bit disappointing when not used on a creature with mutate. So they're either too strong or too weak.

I will still have combat tricks at instant speed that will trigger mutate. But instead of aura boosts, I'm thinking of an enchantment cycle that grants merely a keyword mechanic at a cost. It's more flexible and you can boost a mutated creature each turn if you've got the mana for it. It's a grant of more flexibility in exchange for less strength than a typical aura. I am not sure about the costs or the rarity. I have them in uncommon because they're really not terribly useful in multiples.

I have a feeling they are overcosted. (Still. I actually dropped them all down from four to three mana to cast when making the mock-ups.)

The flavor of the cards refers to the massive amount of overgrowth making it difficult for people to communicate between distances. Essentially all the growth has caused Guthreham to devolve backwards from an early Renaissance society to a more distant, fragmented, and even shamanistic society.