Component Collector

If it's neither day nor night, it becomes day as this creature enters.
Whenever day becomes night or night becomes day, you may tap or untap target nonland permanent.

Island

Sunrise Cavalier

Trample, haste
If it's neither day nor night, it becomes day as this creature enters.
Whenever day becomes night or night becomes day, put a +1/+1 counter on target creature you control.

Obsessive Astronomer

If it's neither day nor night, it becomes day as this creature enters.
Whenever day becomes night or night becomes day, discard up to two cards, then draw that many cards.

Sunstreak Phoenix

Flying
If it's neither day nor night, it becomes day as this creature enters.
Whenever day becomes night or night becomes day, you may pay {1}{R}. If you do, return this card from your graveyard to the battlefield tapped.

The Celestus

If it's neither day nor night, it becomes day as The Celestus enters.
{T}: Add one mana of any color.
{3}, {T}: If it's night, it becomes day. Otherwise, it becomes night. Activate only as a sorcery.
Whenever day becomes night or night becomes day, you gain 1 life. You may draw a card. If you do, discard a card.

Brimstone Vandal

Menace (This creature can't be blocked except by two or more creatures.)
If it's neither day nor night, it becomes day as this creature enters.
Whenever day becomes night or night becomes day, this creature deals 1 damage to each opponent.

Vadrik, Astral Archmage

If it's neither day nor night, it becomes day as Vadrik enters.
Instant and sorcery spells you cast cost {X} less to cast, where X is Vadrik's power.
Whenever day becomes night or night becomes day, put a +1/+1 counter on Vadrik.

Plains

Moonsilver Key

{1}, {T}, Sacrifice this artifact: Search your library for an artifact card with a mana ability or a basic land card, reveal it, put it into your hand, then shuffle.

Gavony Dawnguard

Ward {1}
If it's neither day nor night, it becomes day as this creature enters.
Whenever day becomes night or night becomes day, look at the top four cards of your library. You may reveal a creature card with mana value 3 or less from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Gaea's Blessing

Target player shuffles up to three target cards from their graveyard into their library.
Draw a card.
When this card is put into your graveyard from your library, shuffle your graveyard into your library.

Celestus Sanctifier

If it's neither day nor night, it becomes day as this creature enters.
Whenever day becomes night or night becomes day, look at the top two cards of your library. Put one of them into your graveyard.

Apex of Power

Exile the top seven cards of your library. Until end of turn, you may cast spells from among them.
If this spell was cast from your hand, add ten mana of any one color.

Terramorphic Expanse

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

Mountain

Firmament Sage

If it's neither day nor night, it becomes day as this creature enters.
Whenever day becomes night or night becomes day, draw a card.