Prosperous Innkeeper

When Prosperous Innkeeper enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Whenever another creature you control enters, you gain 1 life.

Consuming Tide

Each player chooses a nonland permanent they control. Return all nonland permanents not chosen this way to their owners' hands. Then you draw a card for each opponent who has more cards in their hand than you.

Verdant Sun's Avatar

Whenever Verdant Sun's Avatar or another creature you control enters, you gain life equal to that creature's toughness.

Negate

Ich-Tekik, Salvage Splicer

When Ich-Tekik, Salvage Splicer enters, create a 3/3 colorless Phyrexian Golem artifact creature token.
Whenever an artifact is put into a graveyard from the battlefield, put a +1/+1 counter on Ich-Tekik and a +1/+1 counter on each Golem you control.
Partner (You can have two commanders if both have partner.)

Volo, Guide to Monsters

Whenever you cast a creature spell that doesn't share a creature type with a creature you control or a creature card in your graveyard, copy that spell. (A copy of a creature spell becomes a token.)

Familiar's Ruse

As an additional cost to cast this spell, return a creature you control to its owner's hand.
Counter target spell.

Zephyr Sentinel

Flash
Flying
When Zephyr Sentinel enters, return up to one other target creature you control to its owner's hand. If it was a Soldier, put a +1/+1 counter on Zephyr Sentinel.

Equilibrium

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

Breeding Pool

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

Man-o'-War

When Man-o'-War enters, return target creature to its owner's hand.

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Words of Wind

{1}: The next time you would draw a card this turn, each player returns a permanent they control to its owner's hand instead.

Aluren

Any player may cast creature spells with mana value 3 or less without paying their mana costs and as though they had flash.

Forest

Simic Growth Chamber

Simic Growth Chamber enters tapped.
When Simic Growth Chamber enters, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Moonsnare Specialist

Ninjutsu {2}{U} ({2}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
When Moonsnare Specialist enters, return up to one target creature to its owner's hand.

Wood Elves

When Wood Elves enters, search your library for a Forest card, put that card onto the battlefield, then shuffle.

Cloud of Faeries

Flying
When Cloud of Faeries enters, untap up to two lands.
Cycling {2} ({2}, Discard this card: Draw a card.)

Primeval Bounty

Whenever you cast a creature spell, create a 3/3 green Beast creature token.
Whenever you cast a noncreature spell, put three +1/+1 counters on target creature you control.
Landfall — Whenever a land you control enters, you gain 3 life.

Rhonas's Monument

Green creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, target creature you control gets +2/+2 and gains trample until end of turn.

Island

Yarok's Wavecrasher

When Yarok's Wavecrasher enters, return another creature you control to its owner's hand.

Semblance Anvil

Imprint — When Semblance Anvil enters, you may exile a nonland card from your hand.
Spells you cast that share a card type with the exiled card cost {2} less to cast.

Barrin, Tolarian Archmage

When Barrin, Tolarian Archmage enters, return up to one other target creature or planeswalker to its owner's hand.
At the beginning of your end step, if a permanent was put into your hand from the battlefield this turn, draw a card.

Mercurial Pretender

You may have Mercurial Pretender enter as a copy of a creature you control, except it has "{2}{U}{U}: Return this creature to its owner's hand."

Storm Sculptor

Storm Sculptor can't be blocked.
When Storm Sculptor enters, return a creature you control to its owner's hand.

Cloudstone Curio

Whenever a nonartifact permanent you control enters, you may return another permanent you control that shares a permanent type with it to its owner's hand.

Peregrine Drake

Flying
When Peregrine Drake enters, untap up to five lands.

Kefnet's Monument

Blue creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, target creature an opponent controls doesn't untap during its controller's next untap step.

Springbloom Druid

When Springbloom Druid enters, you may sacrifice a land. If you do, search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Nylea, Keen-Eyed

Indestructible
As long as your devotion to green is less than five, Nylea isn't a creature.
Creature spells you cast cost {1} less to cast.
{2}{G}: Reveal the top card of your library. If it's a creature card, put it into your hand. Otherwise, you may put it into your graveyard.

Faerie Impostor

Flying
When Faerie Impostor enters, sacrifice it unless you return another creature you control to its owner's hand.

Defiler of Dreams

Flying
As an additional cost to cast blue permanent spells, you may pay 2 life. Those spells cost {U} less to cast if you paid life this way. This effect reduces only the amount of blue mana you pay.
Whenever you cast a blue permanent spell, draw a card.

Quickling

Flash (You may cast this spell any time you could cast an instant.)
Flying
When Quickling enters, sacrifice it unless you return another creature you control to its owner's hand.

Skyscanner

Flying
When Skyscanner enters, draw a card.

Aether Adept

When Aether Adept enters, return target creature to its owner's hand.

Snap

Return target creature to its owner's hand. Untap up to two lands.

Evacuation

Return all creatures to their owners' hands.

Mistform Warchief

Creature spells you cast that share a creature type with Mistform Warchief cost {1} less to cast.
{T}: Mistform Warchief becomes the creature type of your choice until end of turn.

Lonis, Cryptozoologist

Whenever another nontoken creature you control enters, investigate.
{T}, Sacrifice X Clues: Target opponent reveals the top X cards of their library. You may put a nonland permanent card with mana value X or less from among them onto the battlefield under your control. That player puts the rest on the bottom of their library in a random order.

Keymaster Rogue

Keymaster Rogue can't be blocked.
When Keymaster Rogue enters, return a creature you control to its owner's hand.

Arctic Merfolk

Kicker—Return a creature you control to its owner's hand. (You may return a creature you control to its owner's hand in addition to any other costs as you cast this spell.)
If Arctic Merfolk was kicked, it enters with a +1/+1 counter on it.

Thorn Mammoth

Trample
Whenever Thorn Mammoth or another creature you control enters, Thorn Mammoth fights up to one target creature you don't control.

Jaheira, Friend of the Forest

Tokens you control have "{T}: Add {G}."
Choose a Background (You can have a Background as a second commander.)

Seal of the Guildpact

As Seal of the Guildpact enters, choose two colors.
Each spell you cast costs {1} less to cast for each of the chosen colors it is.

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Cloud Key

As Cloud Key enters, choose artifact, creature, enchantment, instant, or sorcery.
Spells you cast of the chosen type cost {1} less to cast.

Getaway Car

Haste
Whenever Getaway Car attacks or blocks, return up to one target creature that crewed it this turn to its owner's hand.
Crew 1

Dream Stalker

When Dream Stalker enters, return a permanent you control to its owner's hand.

Shrieking Drake

Flying
When Shrieking Drake enters, return a creature you control to its owner's hand.