Release the Dogs

Create four 1/1 white Dog creature tokens.

Yoshimaru, Ever Faithful

Whenever another legendary permanent you control enters, put a +1/+1 counter on Yoshimaru, Ever Faithful.
Partner (You can have two commanders if both have partner.)

Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Ozolith, the Shattered Spire

If one or more +1/+1 counters would be put on an artifact or creature you control, that many plus one +1/+1 counters are put on it instead.
{1}{G}, {T}: Put a +1/+1 counter on target artifact or creature you control. Activate only as a sorcery.
Cycling {2} ({2}, Discard this card: Draw a card.)

Confront the Unknown

Investigate, then target creature gets +1/+1 until end of turn for each Clue you control. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Floodhound

{3}, {T}: Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Loyal Warhound

Vigilance
When Loyal Warhound enters, if an opponent controls more lands than you, search your library for a basic Plains card, put it onto the battlefield tapped, then shuffle.

Ongoing Investigation

Whenever one or more creatures you control deal combat damage to a player, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
{1}{G}, Exile a creature card from your graveyard: Investigate. You gain 2 life.

Spirited Companion

When Spirited Companion enters, draw a card.

K-9, Mark I

Negative — As long as K-9, Mark I is untapped, other legendary creatures you control have ward {1}.
Affirmative — {1}{U}, {T}: Target legendary creature can't be blocked this turn.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Pack Leader

Other Dogs you control get +1/+1.
Whenever Pack Leader attacks, prevent all combat damage that would be dealt this turn to Dogs you control.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Negate

Isamaru, Hound of Konda

Sophia, Dogged Detective

When Sophia, Dogged Detective enters, create Tiny, a legendary 2/2 green Dog Detective creature token with trample.
{1}, Sacrifice an artifact token: Put a +1/+1 counter on each Dog you control.
Whenever a Dog you control deals combat damage to a player, create a Food token, then investigate.

Inspiring Statuary

Nonartifact spells you cast have improvise. (Your artifacts can help cast those spells. Each artifact you tap after you're done activating mana abilities pays for {1}.)

Tanuki Transplanter

Whenever Tanuki Transplanter or equipped creature attacks, add an amount of {G} equal to its power. Until end of turn, you don't lose this mana as steps and phases end.
Reconfigure {3} ({3}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Faithful Watchdog

Vigilance
Faithful Watchdog enters with three +1/+1 counters on it.

Deduce

Draw a card. Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Selfless Savior

Sacrifice Selfless Savior: Another target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Mirror Entity

Changeling (This card is every creature type.)
{X}: Until end of turn, creatures you control have base power and toughness X/X and gain all creature types.

Heroic Intervention

Permanents you control gain hexproof and indestructible until end of turn.

Resolute Watchdog

Defender
{1}, Sacrifice Resolute Watchdog: Target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Academy Manufactor

If you would create a Clue, Food, or Treasure token, instead create one of each.

Hardened Scales

If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.

Jaheira, Friend of the Forest

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

Flawless Maneuver

If you control a commander, you may cast this spell without paying its mana cost.
Creatures you control gain indestructible until end of turn.

Ainok Survivalist

Megamorph {1}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.)
When Ainok Survivalist is turned face up, destroy target artifact or enchantment an opponent controls.

Mowu, Loyal Companion

Vigilance, trample
If one or more +1/+1 counters would be put on Mowu, Loyal Companion, that many plus one +1/+1 counters are put on it instead.

Rex, Cyber-Hound

Whenever Rex, Cyber-Hound deals combat damage to a player, they mill two cards and you get {E}{E} (two energy counters).
Pay {E}{E}: Choose target creature card in a graveyard. Exile it with a brain counter on it. Activate only as a sorcery.
Rex has all activated abilities of all cards in exile with brain counters on them.

Ainok Bond-Kin

Outlast {1}{W} ({1}{W}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Each creature you control with a +1/+1 counter on it has first strike.

Phelia, Exuberant Shepherd

Flash
Whenever Phelia, Exuberant Shepherd attacks, exile up to one other target nonland permanent. At the beginning of the next end step, return that card to the battlefield under its owner's control. If it entered under your control, put a +1/+1 counter on Phelia.

Idol of Oblivion

{T}: Draw a card. Activate only if you created a token this turn.
{8}, {T}, Sacrifice Idol of Oblivion: Create a 10/10 colorless Eldrazi creature token.

Mushroom Watchdogs

Sacrifice a Food: Put a +1/+1 counter on Mushroom Watchdogs. It gains vigilance until end of turn. Activate only as a sorcery.