Cavern of Souls

As Cavern of Souls enters the battlefield, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

Mirari's Wake

Creatures you control get +1/+1.
Whenever you tap a land for mana, add one mana of any type that land produced.

Vanquisher's Banner

As Vanquisher's Banner enters the battlefield, choose a creature type.
Creatures you control of the chosen type get +1/+1.
Whenever you cast a creature spell of the chosen type, draw a card.

Door of Destinies

As Door of Destinies enters the battlefield, choose a creature type.
Whenever you cast a spell of the chosen type, put a charge counter on Door of Destinies.
Creatures you control of the chosen type get +1/+1 for each charge counter on Door of Destinies.

Ayula, Queen Among Bears

Whenever another Bear enters the battlefield under your control, choose one —
• Put two +1/+1 counters on target Bear.
• Target Bear you control fights target creature you don't control.

Surrak and Goreclaw

Trample
Other creatures you control have trample.
Whenever another nontoken creature enters the battlefield under your control, put a +1/+1 counter on it. It gains haste until end of turn.

Sylvan Anthem

Green creatures you control get +1/+1.
Whenever a green creature enters the battlefield under your control, scry 1.

Kamahl, Heart of Krosa

At the beginning of combat on your turn, creatures you control get +3/+3 and gain trample until end of turn.
{1}{G}: Until end of turn, target land you control becomes a 1/1 Elemental creature with vigilance, indestructible, and haste. It's still a land.
Partner (You can have two commanders if both have partner.)

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.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Basking Broodscale

Devoid (This card has no color.)
{1}{G}: Adapt 1. (If this creature has no +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever one or more +1/+1 counters are put on Basking Broodscale, you may create a 0/1 colorless Eldrazi Spawn creature token with "Sacrifice this creature: Add {C}."

Delighted Halfling

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a legendary spell, and that spell can't be countered.

Herald's Horn

As Herald's Horn enters the battlefield, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

Goreclaw, Terror of Qal Sisma

Creature spells you cast with power 4 or greater cost {2} less to cast.
Whenever Goreclaw, Terror of Qal Sisma attacks, each creature you control with power 4 or greater gets +1/+1 and gains trample until end of turn.

Bloodline Pretender

Changeling (This card is every creature type.)
As Bloodline Pretender enters the battlefield, choose a creature type.
Whenever another creature of the chosen type enters the battlefield under your control, put a +1/+1 counter on Bloodline Pretender.

Mithril Coat

Flash
Indestructible
When Mithril Coat enters the battlefield, attach it to target legendary creature you control.
Equipped creature has indestructible.
Equip {3}

Metallic Mimic

As Metallic Mimic enters the battlefield, choose a creature type.
Metallic Mimic is the chosen type in addition to its other types.
Each other creature you control of the chosen type enters the battlefield with an additional +1/+1 counter on it.

Kudo, King Among Bears

Other creatures have base power and toughness 2/2 and are Bears in addition to their other types.

Adaptive Automaton

As Adaptive Automaton enters the battlefield, choose a creature type.
Adaptive Automaton is the chosen type in addition to its other types.
Other creatures you control of the chosen type get +1/+1.

Nature's Revolt

All lands are 2/2 creatures that are still lands.

Rampaging Yao Guai

Vigilance, trample
Rampaging Yao Guai enters the battlefield with X +1/+1 counters on it.
When Rampaging Yao Guai enters the battlefield, destroy any number of target artifacts and/or enchantments with total mana value X or less.

Realmwalker

Changeling (This card is every creature type.)
As Realmwalker enters the battlefield, choose a creature type.
You may look at the top card of your library any time.
You may cast creature spells of the chosen type from the top of your library.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Crovax, Ascendant Hero

Other white creatures get +1/+1.
Nonwhite creatures get -1/-1.
Pay 2 life: Return Crovax, Ascendant Hero to its owner's hand.

Elesh Norn, Grand Cenobite

Vigilance
Other creatures you control get +2/+2.
Creatures your opponents control get -2/-2.