It's a meaty creature on its own and difficult to kill through combat, making it white's most potent threat.
One problem with mill decks is closing a game quick enough, but with Riverchurn Monument and The Water Crystal added to the roster of Mill tools, that game-win is a lot closer on the horizon than ever before
infinite combos, mass land destruction, mana rocks, etc
During Theros Standard some green devotion decks could produce a lot of mana thanks to Nykthos, Shrine to Nyx
Frodo, Sauron's Bane Relic of Sauron Sauron's Ransom Sauron, Dino Devotee Sauron, Lord of the Rings Sauron, the Dark Lord Sauron, the Lidless Eye Sauron, the Necromancer The Mouth of Sauron
If youre looking for some guidance on how you want to build your deck, Wizards of the Coast created this insert to help break down the main three colour wedges as well as the included two colour sub-themes that run in the set