Cheapest priced copy (Secrets of Strixhaven Commander): $0.49 at Card Kingdom, near mint, their price list as of .
Deekah, Fractal Theorist 
Legendary Creature — Human Wizard · 3/3 · Rare · Commander 2021 · #26
Magecraft — Whenever you cast or copy an instant or sorcery spell, create a 0/0 green and blue Fractal creature token. Put X +1/+1 counters on it, where X is that spell's mana value.
{3}{U}: Target creature token can't be blocked this turn.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
4 printings · $0.49 to $4.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2021 | 26 | Rare | $0.79 | — |
| Commander 2021 | 353 | Rare | $4.49 | — |
| The List | C21-26 | Rare | — | — |
| Secrets of Strixhaven Commander | 193 | Rare | $0.49 | — |
4 rulings from Wizards of the Coast
- 16 April 2021Some effects instruct you to copy an instant or sorcery card in a zone other than the stack. These copies do not cause magecraft abilities to trigger. However, most effects that do this also allow you to cast the copy, and casting the copy will cause magecraft abilities to trigger.
- 16 April 2021If an effect creates multiple copies of an instant or sorcery spell, magecraft abilities trigger once for each copy created by the effect.
- 16 April 2021Each magecraft ability has a different effect, although they all have the same trigger condition, whenever you cast or copy an instant or sorcery spell.
- 16 April 2021If an effect creates a copy of an instant or sorcery spell, this will also cause the magecraft ability to trigger.