Bushmeat Poacher is an excellent example of a reclamation of the design space that has been stripped by the establishment of the Reserved List, created mainly so that card collectors could retain their assets
A Gruul deck can also get away with running Blood Moon and Magus of the Moon, which can be devastating against decks that are three or more colors
You want to design the main effect to have an impact but not necessarily completely derail things, and this falls squarely into that category, allowing for voltron builds to get the maximum value without being totally useless for everyone else
if you cant do it, its just another Ley Druid and should be rated accordingly
Summary Thickest in the Thicket doubles a creature's power and lets you draw cards, giving you a powerful advantage in the game
If this happens, theyll have to take a mulligan