Mana Leak

Counter target spell unless its controller pays {3}.

Gorilla Shaman

{X}{X}{1}: Destroy target noncreature artifact with mana value X.

Thought Scour

Target player mills two cards.
Draw a card.

Dispel

Escape Tunnel

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
{T}, Sacrifice this land: Target creature with power 2 or less can't be blocked this turn.

Natural State

Destroy target artifact or enchantment with mana value 3 or less.

Electrickery

Electrickery deals 1 damage to target creature you don't control.
Overload {1}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Mountain

Forest

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Tolarian Terror

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)

Grapple with the Past

Mill three cards, then you may return a creature or land card from your graveyard to your hand. (To mill three cards, put the top three cards of your library into your graveyard.)

Memory Lapse

Counter target spell. If that spell is countered this way, put it on top of its owner's library instead of into that player's graveyard.

Negate

Moment's Peace

Prevent all combat damage that would be dealt this turn.
Flashback {2}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Island

Nimble Mongoose

Shroud (This creature can't be the target of spells or abilities.)
Threshold — This creature gets +2/+2 as long as seven or more cards are in your graveyard.

Werebear

{T}: Add {G}.
Threshold — This creature gets +3/+3 as long as seven or more cards are in your graveyard.

Mental Note

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Terramorphic Expanse

Insectile Aberration

Delver of Secrets

At the beginning of your upkeep, look at the top card of your library. You may reveal that card. If an instant or sorcery card is revealed this way, transform this creature.