Cheapest priced copy (Ikoria: Lair of Behemoths): $0.35 at Card Kingdom, near mint, their price list as of .
Swallow Whole 
Sorcery · Uncommon · Ikoria: Lair of Behemoths · #35
As an additional cost to cast this spell, tap an untapped creature you control.
Exile target tapped creature. Put a +1/+1 counter on the creature tapped to pay this spell's additional cost.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ikoria: Lair of Behemoths | 35 | Uncommon | $0.35 | $0.49 |
5 rulings from Wizards of the Coast
- 17 April 2020You must tap exactly one creature to cast Swallow Whole; you can’t cast it without tapping a creature, and you can’t tap additional creatures.
- 17 April 2020If an effect copies Swallow Whole, the copy will put a +1/+1 counter on the creature tapped to pay the additional cost of the original spell.
- 17 April 2020If the target creature is an illegal target by the time Swallow Whole tries to resolve, the spell won’t resolve. You won’t put a +1/+1 counter on any creature.
- 17 April 2020You can tap any untapped creature you control, including a creature you haven’t controlled continuously since the beginning of your most recent turn, to pay the additional cost.
- 17 April 2020The target tapped creature will be exiled even if the creature you tapped leaves the battlefield or becomes untapped before Swallow Whole resolves.