Rules PSA: Weird Doctor Who Mechanic Doesn’t Work With Star Trek

Last updated on October 21, 2026

I'm a Doctor, Not a… | Illustration by Joel Chaim Holtzman

Universes Beyond: Star Trek debuted yesterday, and there are quite a few exciting cards in the mix. We’ve got new landfall cards, new wincons, and quite a few new creature types.

One of these creature types isn’t exactly new, and it seems like we’ll only be getting more of it: doctor.

We fittingly saw the first doctor creature back in Universes Beyond: Doctor Who. It returned for Universes Beyond: Fallout, then Duskmourn, and again in Universes Beyond: Marvel Super Heroes. Seems like doctors are here to stay.

There’s one mechanic from Doctor Who that could easily confuse anyone playing with doctors for the first time, so let’s clear a few things up.

Breaking Down Doctor’s Companion

Clara Oswald | Illustration by Marta Nael

Most MTG players know just how absolutely broken the Ikoria companion mechanic was before it got errata’d. Fewer players know that a variant on companion was introduced in Doctor Who: “Doctor’s Companion.” It would actually be more apt to say that it’s a variant on partner, since this mechanic allows you to have two commanders instead of one commander and one companion.

If a card has Doctor’s Companion, it can be your second commander if your first commander is “the doctor.”

Upon first read, it might appear that a card like Clara Oswald could just partner up with something like Phlox, Unorthodox Doctor, or Doctor Strange, Surgeon.

However…this is not the case.

Nitpicking the Rules

The War Doctor | Illustration by Lixin Yin

While Clara will most certainly double the triggers of all of your doctors, there’s a deceptively huge difference between “a doctor” and “the doctor.” Stick with me here.

A doctor simply refers to the creature type doctor. THE doctor is a separate designation altogether. Per WotC’s Doctor Who mechanics article, the doctor means “a legendary Time Lord Doctor creature with no other creature types.”

Alas, this means that Bill Potts cannot partner up with [/card]Dr. Beverly Crusher[/card]. Morophon, the Boundless can never be the doctor because it has creature types other than time lord and doctor.

While Clara Oswald is basically a 6-mana Roaming Throne in the 99 of doctor typal decks, it can never be paired with The Doctor, E.M.H. in the command zone…even though that one is literally called The Doctor.

Wrap Up

Rules Lawyer | Illustration by Sean Murray

The insanely expansive MTG rules are all about semantics. Just one word can make all the difference in the world.

Companion was broken until fixed, and the partner mechanic currently runs rampant in the meta of high power commander. It’s cool that WotC balanced out Doctor’s Companion by instituting stricter deckbuilding rules…but it is slightly unfortunate that they couldn’t print that whole “Time Lord Doctor” stipulation on cards, especially given that it’s a surefire bet we’ll be getting more creatures with the doctor type in the future.