Just simply having a foretell card exiled is going to make your opponent concerned, and Mammoth Growth is a completely reasonable card once you finally do pull the trigger on it
(To mill a card, put the top card of your library into your graveyard.) Illustrated by Vincent Christiaens Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Not Legal Modern Not Legal Brawl Not Legal Legacy Legal Comp
Its been fine-tuned since then, though Kethis remains banned in Pioneer for the sins of Mox Amber
This artifact is expensive because it does so much work for so little mana investment
At the beginning of your end step if you descended this turn, each opponent may discard, sacrifice a permanent, or take 3 damage from Zoyowa Lava-Tongue
These are generically powerful pieces that synergize with the deck as a whole and deserve a mention