Cheapest priced copy (Alliances): $0.35 at Card Kingdom, near mint, their price list as of .
Phantasmal Fiend 
Creature — Illusion · 1/5 · Common · Alliances · #57b
{B}: This creature gets +1/-1 until end of turn.
{1}{U}: Switch this creature's power and toughness until end of turn.
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
5 printings · $0.35 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Alliances | 57a | Common | $0.35 | — |
| Alliances | 57b | Common | $0.35 | — |
| Coldsnap Theme Decks | 57a | Common | $0.35 | — |
| Deckmasters | 8a | Common | $0.35 | — |
| Deckmasters | 8b | Common | $0.35 | — |
5 rulings from Wizards of the Coast
- 1 November 2005Note that the wording "Effects that alter the creature's power alter its toughness instead, and vice versa, this turn" has been removed.
- 1 October 2008Effects that switch power and toughness are always applied last when determining a creature's power and toughness, even if other power/toughness-changing effects are created later in the turn. For example, if you activate Phantasmal Fiend's first ability, it will become 2/4. Then if you activate its second ability, it will become 4/2. Then if you activate its first ability again, it will become 3/3.
- 19 March 2021Because damage remains marked on a creature until the damage is removed as the turn ends, nonlethal damage dealt to a creature may become lethal if you switch its power and toughness during that turn.
- 19 March 2021Effects that switch a creature's power and toughness apply after all other effects, regardless of when those effects began to apply. For instance, if you target a 1/2 creature then give it +2/+0 later in the turn, it's a 2/3 creature, not a 4/1 creature.
- 19 March 2021Switching a creature's power and toughness twice (or any even number of times) effectively returns the creature to the power and toughness it had before any switches.