It also asks a couple of questions of deckbuilders considering it: "How much do you want a bunch of 1/1 Insects, and are you willing to play mono-green to get them?" Looking at the available data, the answer seems to be, "not all that often." That is, unless you're running an Insect kindred Commander deck with Zask, Skittering Swarmlord, Xira, the Golden Sting, or Vrestin, Menoptra Leader, in which case the answer is still just "sometimes." 14
1 Vohar, Vodalian Desecrator
If a card would receive a 0, meaning it will see no play in that format ever, its rating is left off the list
You get to eight mana, you have this, you win
If a player is instructed to mill more than one card, Glowing One's last ability will trigger once for each nonland card they mill during that instruction