Gen, Confider of Ages

Horsemanship

The Horizon Seeker gets +1/+1 for each different named keyword and ability word among permanents you control and instant or sorcery cards in your graveyard. (For example, flying, landfall, and scry count. Flavor words, like "Magical Tinkering", or game terms like "enchant creature" and "mana" do not.)

Legendary creatures you control get +X/+X, where X is the number of legendary creatures you control.

Whenever you cast a legendary spell from your hand, exile cards from the top of your library until you exile a legendary nonland card with lesser mana value. You may cast that card without paying its mana cost. Put the rest on the bottom of your library in a random order.

As Rukarumel enters, choose a creature type.

Slivers you control and nontoken creatures you control are the chosen type in addition to their other creature types. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

, : Create a 1/1 colorless Sliver creature token.

If The Snapstone Wielder is your commander and your deck contains no land cards, your starting hand size is four and for the rest of the game, at the beginning of your upkeep, you get a mana counter. During each of your turns, you can spend mana of any color equal to the number of mana counters you have. (You want mana on opponent's turns, you're on your own. Who needs instant-speed interaction—)

Whenever The Snapstone Wielder enters or attacks, cast a random nonland Magic card without paying its mana cost. If it has targets, choose the targets at random.

Flying, hexproof from multicolored

Whenever Niv-Mizzet deals combat damage to a player, it deals X damage to any target, target player draws X cards, and you gain X life, where X is the number of different color pairs among permanents you control that are exactly two colors.

Changeling (This card is every creature type.)

As the game begins, if this creature is your commander, choose two creature types. For the rest of the game, treat those two types like they're the same among your creatures and creature cards everywhere.

, : Choose a creature type. Draw a card for each creature you control of that type.