Cheapest priced copy (The List): $20.99 at Card Kingdom, near mint, their price list as of .
Tiamat 
Legendary Creature — Dragon God · 7/7 · Mythic · Adventures in the Forgotten Realms · #298
Flying
When Tiamat enters, if you cast it, search your library for up to five Dragon cards not named Tiamat that each have different names, reveal them, put them into your hand, then shuffle.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
7 printings · $20.99 to $299.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Adventures in the Forgotten Realms | 235 | Mythic | $21.99 | $34.99 |
| Adventures in the Forgotten Realms | 298 | Mythic | $34.99 | $74.99 |
| Adventures in the Forgotten Realms Promos | 235a | Mythic | — | $299.99 |
| Adventures in the Forgotten Realms Promos | 235p | Mythic | $32.99 | $59.99Out of stock |
| Adventures in the Forgotten Realms Promos | 235s | Mythic | — | $39.99Out of stock |
| The List | AFR-235 | Mythic | $20.99 | — |
| Secret Lair Drop | 1017 | Mythic | — | $139.99Out of stock |
2 rulings from Wizards of the Coast
- 23 July 2021A Dragon card is a card with the creature type Dragon in its type line. A card that has “Dragon” in the name (such as Dragon's Disciple) isn't a Dragon card unless it also has the Dragon creature type.
- 23 July 2021Tiamat's enters-the-battlefield ability will trigger if you cast Tiamat from any zone, not just from your hand. Still thinking command zone over here.