The Thirteenth Doctor

Paradox — Whenever you cast a spell from anywhere other than your hand, put a +1/+1 counter on target creature.
Team TARDIS — At the beginning of your end step, untap each creature you control with a counter on it.

Jenny Flint

Partner with Madame Vastra
First strike
Training (Whenever this creature attacks with another creature with greater power, put a +1/+1 counter on this creature.)
Whenever you sacrifice a Clue or Food, put a +1/+1 counter on another target creature you control.

Strax, Sontaran Nurse

Vigilance, trample
Grenades! — {2}, {T}, Sacrifice an artifact: Choose a player at random. When you do, Strax fights another target creature that player controls.
Glory of Battle — Whenever Strax deals damage to a creature, put a +1/+1 counter on Strax.

Kami of Whispered Hopes

If one or more +1/+1 counters would be put on a permanent you control, that many plus one +1/+1 counters are put on that permanent instead.
{T}: Add X mana of any one color, where X is Kami of Whispered Hopes's power.

Ulvenwald Tracker

{1}{G}, {T}: Target creature you control fights another target creature.

Duggan, Private Detective

Duggan's power and toughness are each equal to the number of cards in your hand.
Whenever Duggan enters the battlefield or attacks, investigate.
The Most Important Punch in History — {1}{G}, {T}: Duggan deals damage equal to twice its power to another target creature. Activate only once.

Clan Crafter

Commander creatures you own have "{2}, Sacrifice an artifact: Put a +1/+1 counter on this creature and draw a card."

The Goose Mother

Flying
The Goose Mother enters the battlefield with X +1/+1 counters on it.
When The Goose Mother enters the battlefield, create half X Food tokens, rounded up.
Whenever The Goose Mother attacks, you may sacrifice a Food. If you do, draw a card.

Wavesifter

Flying
When Wavesifter enters the battlefield, investigate twice. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Evoke {G}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters the battlefield.)

Lonis, Cryptozoologist

Whenever another nontoken creature enters the battlefield under your control, 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.

Ace, Fearless Rebel

Nitro-9 — Whenever Ace, Fearless Rebel attacks, you may sacrifice an artifact. When you do, put a +1/+1 counter on Ace, Fearless Rebel, then it fights up to one target creature defending player controls.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Reckless Fireweaver

Whenever an artifact enters the battlefield under your control, Reckless Fireweaver deals 1 damage to each opponent.

Heaven Sent

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Investigate.
III — Heaven Sent deals 1 damage to each opponent. Then if an opponent has 0 or less life, draw seven cards. Otherwise, exile Heaven Sent and you may cast it this turn.

Ethereal Investigator

Flying
When Ethereal Investigator enters the battlefield, investigate X times, where X is the number of opponents you have. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Whenever you draw your second card each turn, create a 1/1 white Spirit creature token with flying.

Swiftfoot Boots

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

Breya's Apprentice

When Breya's Apprentice enters the battlefield, create a 1/1 colorless Thopter artifact creature token with flying.
{T}, Sacrifice an artifact: Choose one —
• Exile the top card of your library. Until the end of your next turn, you may play that card.
• Target creature gets +2/+0 until end of turn.

The Fugitive Doctor

When The Fugitive Doctor enters the battlefield, investigate.
Whenever The Fugitive Doctor attacks, you may sacrifice a Clue. When you do, target instant or sorcery card in your graveyard gains flashback {2}{R}{G} until end of turn. (You may cast that card from your graveyard for its flashback cost. Then exile it.)

Tireless Provisioner

Landfall — Whenever a land enters the battlefield under your control, create a Food token or a Treasure token. (Food is an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life." Treasure is an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Tireless Tracker

Landfall — Whenever a land enters the battlefield under your control, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Whenever you sacrifice a Clue, put a +1/+1 counter on Tireless Tracker.

Halana and Alena, Partners

First strike, reach
At the beginning of combat on your turn, put X +1/+1 counters on another target creature you control, where X is Halana and Alena's power. That creature gains haste until end of turn.

Sarinth Steelseeker

Whenever an artifact enters the battlefield under your control, look at the top card of your library. If it's a land card, you may reveal it and put it into your hand. If you don't put the card into your hand, you may put it into your graveyard.

Madame Vastra

Partner with Jenny Flint (When this creature enters the battlefield, target player may put Jenny Flint into their hand from their library, then shuffle.)
Madame Vastra must be blocked if able.
Whenever a creature dealt damage by Madame Vastra this turn dies, create a Clue token and a Food token.

Syr Ginger, the Meal Ender

Syr Ginger, the Meal Ender has trample, hexproof, and haste as long as an opponent controls a planeswalker.
Whenever another artifact you control is put into a graveyard from the battlefield, put a +1/+1 counter on Syr Ginger and scry 1.
{2}, {T}, Sacrifice Syr Ginger: You gain life equal to its power.

Ingenious Artillerist

Whenever one or more artifacts enter the battlefield under your control, Ingenious Artillerist deals that much damage to each opponent.

Peregrin Took

If one or more tokens would be created under your control, those tokens plus an additional Food token are created instead. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
Sacrifice three Foods: Draw a card.

Shimmer Dragon

Flying
As long as you control four or more artifacts, Shimmer Dragon has hexproof.
Tap two untapped artifacts you control: Draw a card.

Beast Within

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

Kappa Cannoneer

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Ward {4}
Whenever Kappa Cannoneer or another artifact enters the battlefield under your control, put a +1/+1 counter on Kappa Cannoneer and it can't be blocked this turn.

Evolution Sage

Landfall — Whenever a land enters the battlefield under your control, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Hedron Detonator

Whenever an artifact enters the battlefield under your control, Hedron Detonator deals 1 damage to target opponent.
{T}, Sacrifice two artifacts: Exile the top card of your library. You may play that card this turn.

Heroic Intervention

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

Martha Jones

Woman Who Walked the Earth — When Martha Jones enters the battlefield, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Whenever you sacrifice a Clue, Martha Jones and up to one other target creature can't be blocked this turn.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Gilded Goose

Flying
When Gilded Goose enters the battlefield, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
{1}{G}, {T}: Create a Food token.
{T}, Sacrifice a Food: Add one mana of any color.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Danny Pink

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Creatures you control have "Whenever one or more counters are put on this creature for the first time each turn, draw a card."

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Nyssa of Traken

You have no maximum hand size.
Sonic Booster — Whenever Nyssa of Traken attacks, sacrifice X artifacts. When you sacrifice one or more artifacts this way, tap up to X target creatures and you draw X cards.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Academy Manufactor

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

Neyith of the Dire Hunt

Whenever one or more creatures you control fight or become blocked, draw a card.
At the beginning of combat on your turn, you may pay {2}{R/G}. If you do, double target creature's power until end of turn. That creature must be blocked this combat if able. ({R/G} can be paid with either {R} or {G}.)

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.