Cheapest priced copy (Commander 2015): $0.35 at Card Kingdom, near mint, their price list as of .
Snakeform 
Instant · Common · Ravnica: Clue Edition · #209
Until end of turn, target creature loses all abilities and becomes a green Snake with base power and toughness 1/1.
Draw a card.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
3 printings · $0.35 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2015 | 242 | Common | $0.35 | — |
| Ravnica: Clue Edition | 209 | Common | $0.35 | — |
| Eventide | 161 | Common | $0.35 | $1.49 |
4 rulings from Wizards of the Coast
- 1 August 2008If the affected creature gains an ability after Snakeform resolves, it will keep that ability.
- 1 August 2008Snakeform doesn't counter abilities that have already triggered or been activated. In particular, there is no way to cast this to stop a creature's "At the beginning of your upkeep" or "When this creature enters" abilities from triggering.
- 1 August 2008If Snakeform affects a creature with changeling, the creature will lose its changeling ability, and will no longer be all creature types.
- 1 October 2009The power/toughness-setting effect overwrites other effects that set power and toughness only if those effects existed before this spell resolved. It will not overwrite effects that modify power or toughness (whether from a static ability, counters, or a resolved spell or ability), nor will it overwrite effects that set power and toughness which come into existence after this spell resolves. Effects that switch the creature's power and toughness are always applied after any other power or toughness changing effects, including this one, regardless of the order in which they are created.