Lazav, Wearer of Faces

Whenever Lazav attacks, exile target card from a graveyard, then investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Whenever you sacrifice a Clue, you may have Lazav become a copy of a creature card exiled with it until end of turn.

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.

Fire Nation Warship

Reach
When this Vehicle dies, create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Crew 2 (Tap any number of creatures you control with total power 2 or more: This Vehicle becomes an artifact creature until end of turn.)

Ruinous Waterbending

As an additional cost to cast this spell, you may waterbend {4}. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)
All creatures get -2/-2 until end of turn. If this spell's additional cost was paid, whenever a creature dies this turn, you gain 1 life.

Waterbender's Restoration

As an additional cost to cast this spell, waterbend {X}. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)
Exile X target creatures you control. Return those cards to the battlefield under their owner's control at the beginning of the next end step.

Nightmares and Daydreams

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after IV.)
I, II, III — Until your next turn, whenever you cast an instant or sorcery spell, target player mills cards equal to that spell's mana value.
IV — Draw a card. If a graveyard has twenty or more cards in it, draw three cards instead.

Forecasting Fortune Teller

When this creature enters, create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")

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.)

Giant Koi

Waterbend {3}: This creature can't be blocked this turn. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)
Islandcycling {2} ({2}, Discard this card: Search your library for an Island card, reveal it, put it into your hand, then shuffle.)

Secret of Bloodbending

As an additional cost to cast this spell, you may waterbend {10}.
You control target opponent during their next combat phase. If this spell's additional cost was paid, you control that player during their next turn instead. (You see all cards that player could see and make all decisions for them.)
Exile Secret of Bloodbending.

Island

Hama, the Bloodbender

When Hama enters, target opponent mills three cards. Exile up to one noncreature, nonland card from that player's graveyard. For as long as you control Hama, you may cast the exiled card during your turn by waterbending {X} rather than paying its mana cost, where X is its mana value. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)

Messenger Hawk

Flying
When this creature enters, create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")
This creature gets +2/+0 as long as you've drawn two or more cards this turn.

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."

Lost Days

The owner of target creature or enchantment puts it into their library second from the top or on the bottom. You create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")

The Mechanist, Aerial Artisan

Whenever you cast a noncreature spell, create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")
{T}: Until end of turn, target artifact token you control becomes a 3/1 Construct artifact creature with flying.

Swamp

Water Whip

As an additional cost to cast this spell, waterbend {5}. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)
Return up to two target creatures to their owners' hands. Draw two cards.

Sold Out

Exile target creature. If it was dealt damage this turn, create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Geyser Leaper

Flying
Waterbend {4}: Draw a card, then discard a card. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)

Lo and Li, Royal Advisors

Whenever an opponent discards a card or mills one or more cards, put a +1/+1 counter on each Advisor you control.
{2}{U/B}: Target player mills four cards. (They put the top four cards of their library into their graveyard.)

Ruthless Waterbender

Waterbend {2}: This creature gets +1/+1 until end of turn. Activate only during your turn. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)

The Unagi of Kyoshi Island

Flash
Ward—Waterbend {4}. (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {4}. They can tap their artifacts and creatures to help. Each one pays for {1}.)
Whenever an opponent draws their second card each turn, you draw two cards.

Obsessive Pursuit

When this enchantment enters and at the beginning of your upkeep, you lose 1 life and create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Whenever you attack, put X +1/+1 counters on target attacking creature, where X is the number of permanents you've sacrificed this turn. If X is three or greater, that creature gains lifelink until end of turn.

Foggy Swamp Visions

As an additional cost to cast this spell, waterbend {X}. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)
Exile X target creature cards from graveyards. For each creature card exiled this way, create a token that's a copy of it. At the beginning of your next end step, sacrifice those tokens.

Tiger-Seal

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

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.")

Waterbending Lesson

Draw three cards. Then discard a card unless you waterbend {2}. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)

Callous Inspector

Menace (This creature can't be blocked except by two or more creatures.)
When this creature dies, it deals 1 damage to you. Create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")