I heard whispers that the holiness of Yggdrasil increases Luck aswell ;)
That would look like this:
Strong roots (Requires Yggdrasil lvl99)
Every 6 sec all nature towers gain 5% DMG/critdmg, 0.5%(or 0.25%) critchance and 0.05%(or less) Luck
(custom status #)
Some less critchance but with addition of Luck. That way beavers would be more viable in late game i think.