Curious Obsession

Enchant creature
Enchanted creature gets +1/+1 and has "Whenever this creature deals combat damage to a player, you may draw a card."
At the beginning of your end step, if you didn't attack with a creature this turn, sacrifice Curious Obsession.

Kaseto, Orochi Archmage

{G}{U}: Target creature can't be blocked this turn. If that creature is a Snake, it gets +2/+2 until end of turn.

Dreamroot Cascade

Dreamroot Cascade enters the battlefield tapped unless you control two or more other lands.
{T}: Add {G} or {U}.

Flooded Grove

{T}: Add {C}.
{G/U}, {T}: Add {G}{G}, {G}{U}, or {U}{U}.

Winged Temple of Orazca

(Transforms from Hadana's Climb.)
{T}: Add one mana of any color.
{1}{G}{U}, {T}: Target creature you control gains flying and gets +X/+X until end of turn, where X is its power.

Hadana's Climb

At the beginning of combat on your turn, put a +1/+1 counter on target creature you control. Then if that creature has three or more +1/+1 counters on it, transform Hadana's Climb.

Hadana's Climb // Winged Temple of Orazca

Drover of the Mighty

Drover of the Mighty gets +2/+2 as long as you control a Dinosaur.
{T}: Add one mana of any color.

Universal Automaton

Changeling (This card is every creature type.)

Equilibrium

Whenever you cast a creature spell, you may pay {1}. If you do, return target creature to its owner's hand.

Ghalta, Primal Hunger

This spell costs {X} less to cast, where X is the total power of creatures you control.
Trample

Witness Protection

Enchant creature
Enchanted creature loses all abilities and is a green and white Citizen creature with base power and toughness 1/1 named Legitimate Businessperson. (It loses all other colors, card types, creature types, and names.)

Cherished Hatchling

When Cherished Hatchling dies, you may cast Dinosaur spells this turn as though they had flash, and whenever you cast a Dinosaur spell this turn, it gains "When this creature enters the battlefield, you may have it fight another target creature."

Bred for the Hunt

Whenever a creature you control with a +1/+1 counter on it deals combat damage to a player, you may draw a card.

Lord of the Unreal

Illusion creatures you control get +1/+1 and have hexproof. (They can't be the targets of spells or abilities your opponents control.)

Abundant Growth

Enchant land
When Abundant Growth enters the battlefield, draw a card.
Enchanted land has "{T}: Add one mana of any color."

Bala Ged Sanctuary

Bala Ged Sanctuary enters the battlefield tapped.
{T}: Add {G}.

Bala Ged Recovery

Return target card from your graveyard to your hand.

Bala Ged Recovery // Bala Ged Sanctuary

Hinterland Harbor

Hinterland Harbor enters the battlefield tapped unless you control a Forest or an Island.
{T}: Add {G} or {U}.

Dissipation Field

Whenever a permanent deals damage to you, return it to its owner's hand.

Aetherize

Return all attacking creatures to their owner's hand.

In Too Deep

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Enchant creature, planeswalker, or Clue
Enchanted permanent is a colorless Clue artifact with "{2}, Sacrifice this artifact: Draw a card" and loses all other abilities. (It's no longer a creature or planeswalker.)

Guardian Gladewalker

Changeling (This card is every creature type.)
When Guardian Gladewalker enters the battlefield, put a +1/+1 counter on target creature.

Prevent all combat damage that would be dealt this turn.

Deepfathom Skulker

Devoid (This card has no color.)
Whenever a creature you control deals combat damage to a player, you may draw a card.
{3}{C}: Target creature can't be blocked this turn. ({C} represents colorless mana.)

Mutavault

{T}: Add {C}.
{1}: Mutavault becomes a 2/2 creature with all creature types until end of turn. It's still a land.

Curiosity

Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.

Turntimber, Serpentine Wood

As Turntimber, Serpentine Wood enters the battlefield, you may pay 3 life. If you don't, it enters the battlefield tapped.
{T}: Add {G}.

Turntimber Symbiosis

Look at the top seven cards of your library. You may put a creature card from among them onto the battlefield. If that card has mana value 3 or less, it enters with three additional +1/+1 counters on it. Put the rest on the bottom of your library in a random order.

Turntimber Symbiosis // Turntimber, Serpentine Wood

Arcane Adaptation

As Arcane Adaptation enters the battlefield, choose a creature type.
Creatures you control are the chosen type in addition to their other types. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

Shapers' Sanctuary

Whenever a creature you control becomes the target of a spell or ability an opponent controls, you may draw a card.

Galerider Sliver

Sliver creatures you control have flying.

Arlinn's Wolf

Arlinn's Wolf can't be blocked by creatures with power 2 or less.

Infiltration Lens

Whenever equipped creature becomes blocked by a creature, you may draw two cards.
Equip {1}

Military Intelligence

Whenever you attack with two or more creatures, draw a card.

Forest

Keen Sense

Tidechannel Pathway

Barkchannel Pathway

Barkchannel Pathway // Tidechannel Pathway

Alora, Merry Thief

Whenever you attack, up to one target attacking creature can't be blocked this turn. Return that creature to its owner's hand at the beginning of the next end step.
Choose a Background (You can have a Background as a second commander.)

Island

Pygmy Hippo

Whenever Pygmy Hippo attacks and isn't blocked, you may have defending player activate a mana ability of each land they control and lose all unspent mana. If you do, Pygmy Hippo assigns no combat damage this turn and at the beginning of your next main phase this turn, you add an amount of {C} equal to the amount of mana that player lost this way.

Combat Research

Enchant creature
Enchanted creature has "Whenever this creature deals combat damage to a player, draw a card."
As long as enchanted creature is legendary, it gets +1/+1 and has ward {1}. (Whenever enchanted creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)

Goggles of Night

Whenever equipped creature deals combat damage to a player, scry 1, then draw a card. (To scry 1, look at the top card of your library, then you may put that card on the bottom of your library.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

The Bears of Littjara

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create a 2/2 blue Shapeshifter creature token with changeling.
II — Any number of target Shapeshifter creatures you control have base power and toughness 4/4.
III — Choose up to one target creature or planeswalker. Each creature with power 4 or greater you control deals damage equal to its power to that permanent.