Rory Williams

Partner with Amy Pond
First strike, lifelink
The Last Centurion — When you cast this spell from anywhere other than exile, exile it with three time counters on it. It gains suspend. Then investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

The Eleventh Doctor

I. AM. TALKING! — Whenever The Eleventh Doctor deals combat damage to a player, you may exile a card from your hand with a number of time counters on it equal to its mana value. If it doesn't have suspend, it gains suspend.
{2}: Target creature with power 3 or less can't be blocked this turn.

Flaming Tyrannosaurus

Menace
Paradox — Whenever you cast a spell from anywhere other than your hand, Flaming Tyrannosaurus deals 3 damage to any target. Then put a +1/+1 counter on Flaming Tyrannosaurus.
When Flaming Tyrannosaurus dies, it deals damage equal to its power to each opponent.

Wibbly-wobbly, Timey-wimey

Time travel. (For each suspended card you own and each permanent you control with a time counter on it, you may add or remove a time counter.)
Draw a card.

Teferi, Hero of Dominaria

+1: Draw a card. At the beginning of the next end step, untap up to two lands.
−3: Put target nonland permanent into its owner's library third from the top.
−8: You get an emblem with "Whenever you draw a card, exile target permanent an opponent controls."

Amy Pond

Partner with Rory Williams (When this creature enters, target player may put Rory into their hand from their library, then shuffle.)
Whenever Amy Pond deals combat damage to a player, choose a suspended card you own and remove that many time counters from it.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Judoon Enforcers

Trample
No more than one creature can attack you each combat.
Suspend 6—{1}{R}{W} (Rather than cast this card from your hand, you may pay {1}{R}{W} and exile it with six time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost. It has haste.)

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."

The Pandorica

You may choose not to untap The Pandorica during your untap step.
{1}{W}, {T}: Untap another target nonland permanent, then it phases out. It can't phase in for as long as The Pandorica remains tapped. When The Pandorica becomes untapped or leaves the battlefield, that permanent phases in. Activate only as a sorcery.

Time Beetle

Skulk (This creature can't be blocked by creatures with greater power.)
Parallel Universe — Whenever Time Beetle deals combat damage to a player, time travel. (For each suspended card you own and each permanent you control with a time counter on it, you may add or remove a time counter.)

The Moment

At the beginning of your upkeep, put a time counter on The Moment.
{2}, {T}: Untap target creature you control. It phases out until The Moment leaves the battlefield.
{3}, {T}: Destroy each nonland permanent with mana value less than or equal to the number of time counters on The Moment. Then sacrifice The Moment. Activate only as a sorcery.

The Eleventh Hour

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Search your library for a Doctor card, reveal it, put it into your hand, then shuffle.
II — Create a Food token and a 1/1 white Human creature token with "Doctor spells you cast cost {1} less to cast."
III — Create a token that's a copy of target creature, except it's a legendary Alien named Prisoner Zero.

The War Doctor

Whenever one or more other permanents phase out and whenever one or more other cards are put into exile from anywhere, put a time counter on The War Doctor.
Whenever The War Doctor attacks, it deals damage equal to the number of time counters on it to any target. If a creature dealt damage this way would die this turn, exile it instead.

Regenerations Restored

Vanishing 12 (This enchantment enters with twelve time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
Whenever one or more time counters are removed from Regenerations Restored, scry 1 and you gain 1 life. Then if Regenerations Restored has no time counters on it, exile it. When you do, take an extra turn after this one.

Teferi, Master of Time

You may activate loyalty abilities of Teferi, Master of Time on any player's turn any time you could cast an instant.
+1: Draw a card, then discard a card.
−3: Target creature you don't control phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)
−10: Take two extra turns after this one.