Undercity Sewers

({T}: Add {U} or {B}.)
This land enters tapped.
When this land enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Gloomlake Verge

{T}: Add {U}.
{T}: Add {B}. Activate only if you control an Island or a Swamp.

Watery Grave

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

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

Knowledge Seeker

Vigilance
Whenever you draw your second card each turn, put a +1/+1 counter on this creature.
When this creature dies, create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Raven Eagle

Flying
Whenever this creature enters or attacks, exile up to one target card from a graveyard. If a creature card is exiled this way, create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Whenever you draw your second card each turn, each opponent loses 1 life and you gain 1 life.

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Wolfbat

Flying
Whenever you draw your second card each turn, you may pay {B}. If you do, return this card from your graveyard to the battlefield with a finality counter on it. (If a creature with a finality counter on it would die, exile it instead.)

Fabled Passage

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control four or more lands, untap that land.

Abandon Attachments

You may discard a card. If you do, draw two cards.

Swamp

Otter-Penguin

Whenever you draw your second card each turn, this creature gets +1/+2 until end of turn and can't be blocked this turn.

Consider

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

Boomerang Basics

Return target nonland permanent to its owner's hand. If you controlled that permanent, draw a card.

Agna Qel'a

This land enters tapped unless you control a basic land.
{T}: Add {U}.
{2}{U}, {T}: Draw a card, then discard a card.

It'll Quench Ya!

Counter target spell unless its controller pays {2}.

Tiger-Seal

Vigilance
At the beginning of your upkeep, tap this creature.
Whenever you draw your second card each turn, untap this creature.

Foggy Swamp Spirit Keeper

Lifelink
Whenever you draw your second card each turn, create a 1/1 colorless Spirit creature token with "This token can't block or be blocked by non-Spirit creatures."

Brainstorm

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

Island

Heartless Act

Choose one —
• Destroy target creature with no counters on it.
• Remove up to three counters from target creature.