Haggle

You may discard a card. If you do, draw a card. (Then exile this card. You may cast the creature later from exile.)

Merchant of the Vale

Merchant of the Vale // Haggle

Frantic Inventory

Draw a card, then draw cards equal to the number of cards named Frantic Inventory in your graveyard.

Manamorphose

Add two mana in any combination of colors.
Draw a card.

Snow-Covered Island

Stormwing Entity

This spell costs {2}{U} less to cast if you've cast an instant or sorcery spell this turn.
Flying
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Stormwing Entity enters, scry 2.

Wooded Foothills

{T}, Pay 1 life, Sacrifice Wooded Foothills: Search your library for a Mountain or Forest card, put it onto the battlefield, then shuffle.

Monastery Swiftspear

Haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Snow-Covered Mountain

Steam Vents

({T}: Add {U} or {R}.)
As Steam Vents enters, you may pay 2 life. If you don't, it enters tapped.

Soul-Scar Mage

Prowess
If a source you control would deal noncombat damage to a creature an opponent controls, put that many -1/-1 counters on that creature instead.

Mountain

Island

Sprite Dragon

Flying, haste
Whenever you cast a noncreature spell, put a +1/+1 counter on Sprite Dragon.

Flooded Strand

{T}, Pay 1 life, Sacrifice Flooded Strand: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle.

Mutagenic Growth

({G/P} can be paid with either {G} or 2 life.)
Target creature gets +2/+2 until end of turn.