Striped Riverwinder

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Cycling {U} ({U}, Discard this card: Draw a card.)

Urza's Mine

{T}: Add {C}. If you control an Urza's Power-Plant and an Urza's Tower, add {C}{C} instead.

{T}: Add {C}. If you control an Urza's Mine and an Urza's Tower, add {C}{C} instead.

{T}: Add {C}. If you control an Urza's Mine and an Urza's Power-Plant, add {C}{C}{C} instead.

{1}, {T}, Sacrifice Chromatic Sphere: Add one mana of any color. Draw a card.

When Prophetic Prism enters, draw a card.
{1}, {T}: Add one mana of any color.

Flying
Cycling {U} ({U}, Discard this card: Draw a card.)
When you cycle Windcaller Aven, target creature gains flying until end of turn.

Return target creature to its owner's hand. Untap up to two lands.

Flying
When Mulldrifter enters, draw two cards.
Evoke {2}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Look at the top four cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order.