Myr Battlesphere

When Myr Battlesphere enters the battlefield, create four 1/1 colorless Myr artifact creature tokens.
Whenever Myr Battlesphere attacks, you may tap X untapped Myr you control. If you do, Myr Battlesphere gets +X/+0 until end of turn and deals X damage to the player or planeswalker it's attacking.

Forest

Urza's Power Plant

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

Prophetic Prism

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

Urza's Tower

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

Urza's Mine

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

Explore

You may play an additional land this turn.
Draw a card.

Accumulated Knowledge

Draw a card, then draw cards equal to the number of cards named Accumulated Knowledge in all graveyards.

Bane of Bala Ged

Whenever Bane of Bala Ged attacks, defending player exiles two permanents they control.

Adventurous Impulse

Look at the top three cards of your library. You may reveal a creature or land card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Terrarion

Terrarion enters the battlefield tapped.
{2}, {T}, Sacrifice Terrarion: Add two mana in any combination of colors.
When Terrarion is put into a graveyard from the battlefield, draw a card.

Chromatic Sphere

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

Nature's Claim

Destroy target artifact or enchantment. Its controller gains 4 life.

Island

Sylvan Scrying

Search your library for a land card, reveal it, put it into your hand, then shuffle.

Barbed Sextant

{1}, {T}, Sacrifice Barbed Sextant: Add one mana of any color. Draw a card at the beginning of the next turn's upkeep.