Cheapest priced copy (The Lost Caverns of Ixalan): $0.35 at Card Kingdom, near mint, their price list as of .
Guardian of the Great Door 
Creature — Angel · 4/4 · Uncommon · The Lost Caverns of Ixalan · #16
As an additional cost to cast this spell, tap four untapped artifacts, creatures, and/or lands you control.
Flying
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The Lost Caverns of Ixalan | 16 | Uncommon | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 10 November 2023You can tap any four untapped artifacts, creatures, and/or lands you control, including creatures you haven't controlled continuously since the beginning of your most recent turn, to pay the additional cost to cast Guardian of the Great Door.