Cheapest priced copy (Doctor Who): $0.59 at Card Kingdom, near mint, their price list as of .
The Twelfth Doctor 
Legendary Creature — Time Lord Doctor · 4/4 · Rare · Doctor Who · #164
The first spell you cast from anywhere other than your hand each turn has demonstrate. (When you cast that spell, you may copy it. If you do, choose an opponent to also copy it. A copy of a permanent spell becomes a token.)
Whenever you copy a spell, put a +1/+1 counter on The Twelfth Doctor.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
7 printings · $0.49 to $15.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Doctor Who | 164 | Rare | $0.59 | $0.49 |
| Doctor Who | 449 | Rare | $1.79 | $0.79Out of stock |
| Doctor Who | 563 | Rare | $1.99Out of stock | $1.99 |
| Doctor Who | 563z | Rare | — | — |
| Doctor Who | 769 | Rare | — | $2.99Out of stock |
| Doctor Who | 1040 | Rare | — | $3.49 |
| Doctor Who | 1154 | Rare | — | $15.99 |
11 rulings from Wizards of the Coast
- 13 October 2023This means that if you cast a spell with demonstrate and both you and an opponent copy it, the opponent's copy will resolve first, then your copy will resolve, and finally the original spell will resolve.
- 13 October 2023If the spell requires targets, you choose the target of the original spell as you cast it. If you create a copy of the spell, you may choose new targets for the copy as you create that copy. Similarly, the opponent you chose to create a copy may choose new targets for that copy as it's created. In other words, your opponent will know the targets of your original spell and your copy when choosing the new targets, if any, for their copy.
- 13 October 2023You choose whether to make a copy as the demonstrate ability resolves. This happens before the original spell resolves. Your copy goes on the stack above the original spell.
- 13 October 2023If you cast the spell and choose not to copy it, no opponent will get to copy it either.
- 13 October 2023Neither "Time" nor "Lord" are creature types. Some older cards were printed with the subtype "Lord," but all of those cards have updated Oracle card text that removed that type.
- 13 October 2023If any additional or alternative costs were paid to cast the spell with demonstrate, the copies will see those choices as well. For example, if the spell has a kicker ability and was kicked, the copies will also be kicked.
- 13 October 2023If the spell had an X value chosen for it as it was cast, the copies will have the same value of X.
- 13 October 2023If you copy a spell with demonstrate, you then immediately choose an opponent. If they copy the spell, it goes on top of the stack.
- 13 October 2023If an effect instructs you to choose a creature type, you may choose Time Lord.
- 13 October 2023Unlike other creature types in Magic that are each only one word, the two words "Time Lord" represent a single creature subtype. Time Lord is the only two-word creature type.
- 13 October 2023If the spell with demonstrate had any modes chosen for it as it was cast, the copies will have the same modes chosen for it.