Cheapest priced copy (Rise of the Eldrazi): $0.49 at Card Kingdom, near mint, their price list as of .
Hedron-Field Purists 
Creature — Human Cleric · 0/3 · Rare · Rise of the Eldrazi · #25
Level up {2}{W} ({2}{W}: Put a level counter on this. Level up only as a sorcery.)
LEVEL 1-4
1/4
If a source would deal damage to you or a creature you control, prevent 1 of that damage.
LEVEL 5+
2/5
If a source would deal damage to you or a creature you control, prevent 2 of that damage.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Rise of the Eldrazi | 25 | Rare | $0.49 | $0.49 |
10 rulings from Wizards of the Coast
- 15 June 2010The prevention effects don’t affect damage dealt directly to a planeswalker you control.
- 15 June 2010If a source would deal damage to multiple applicable recipients, the prevention effects apply to each of those recipients separately. For example, if Hedron-Field Purists is level 1 and you cast Earthquake (“Earthquake deals X damage to each creature without flying and each player”) with X equal to 3, that Earthquake will deal 2 damage to you, 2 damage to each creature without flying you control, 3 damage to each other player, and 3 damage to each creature without flying other players control.
- 15 June 2010Effects that modify a leveler’s power or toughness, such as the effects of Giant Growth or Glorious Anthem, will apply to it no matter when they started to take effect. The same is true for counters that change the creature’s power or toughness (such as +1/+1 counters) and effects that switch its power and toughness.
- 15 June 2010Remember that Hedron-Field Purists never has both of these prevention effects at the same time.
- 15 June 2010The effects from multiple Hedron-Field Purists are cumulative.
- 15 June 2010The prevention effects prevent 1 or 2 damage, as applicable, from each source (regardless of who controls it) each time that source would deal damage to you or a creature you control. They prevent damage of any kind, not just combat damage.
- 15 June 2010If another creature becomes a copy of a leveler, all of the leveler’s printed abilities — including those represented by level symbols — are copied. The current characteristics of the leveler, and the number of level counters on it, are not. The abilities, power, and toughness of the copy will be determined based on how many level counters are on the copy.
- 15 June 2010A creature’s level is based on how many level counters it has on it, not how many times its level up ability has been activated or has resolved. If a leveler gets level counters due to some other effect (such as Clockspinning) or loses level counters for some reason (such as Vampire Hexmage), its level is changed accordingly.
- 15 June 2010The abilities a leveler grants to itself don’t overwrite any other abilities it may have. In particular, they don’t overwrite the creature’s level up ability; it always has that.
- 15 June 2010Effects that set a leveler’s power or toughness to a specific value, including the effects from a level symbol’s ability, apply in timestamp order. The timestamp of each level symbol’s ability is the same as the timestamp of the leveler itself, regardless of when the most recent level counter was put on it.