Exploration is a one mana enchantment that allows you to play two lands per turn instead of one
This deck played around 20 enchantments to get triggers off his cast ability to make his legendary fun, like Rhystic Study and Sylvan Library, around 15 Frogs and changelings to use his ability on like Yargle, Glutton of Urborg and The Gitrog Monster and then some Voltron-ish and unblockable elements to get some punches in like Archetype of Imagination and Whispersilk Cloak
(See the aforementioned Ghostway for ideas of other ways to keep people safe.) The only issue I have (other than a mana investment) is that it's harder to build around with things like Darksteel Forge or Bloodghast (tricks you could use with an Oblivion Stone to make things unfair)
Leovold, Emissary of Trest First Printed: 2016-AUG Banned: 2017-APR Leovold as a commander creates an environment of asymmetric resource denial in the early game
#8 This card would be #2 on our list if it werent for its uncommon status
In these kinds of decks, you should almost always play cards from there, have ways to manipulate the top of your library, or shuffle it