Cheapest priced copy (Dominaria United): $0.79 at Card Kingdom, near mint, their price list as of .
Defiler of Faith 
Creature — Phyrexian Human · 5/5 · Rare · Dominaria United · #16
Vigilance
As an additional cost to cast white permanent spells, you may pay 2 life. Those spells cost {W} less to cast if you paid life this way. This effect reduces only the amount of white mana you pay.
Whenever you cast a white permanent spell, create a 1/1 white Soldier creature token.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.79 to $3.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Dominaria United | 16 | Rare | $0.79 | $0.79 |
| Dominaria United | 385 | Rare | $1.49 | $0.99 |
| Dominaria United Promos | 16p | Rare | $2.99 | $3.49 |
| Dominaria United Promos | 16s | Rare | — | $0.99 |
2 rulings from Wizards of the Coast
- 9 September 2022Some players may make the mental shortcut that the Defilers effectively turn one of the colored mana symbols in the spell’s cost into a Phyrexian colored mana symbol. Despite the similarity in function, this ability does not cause the spells to have Phyrexian mana symbols in their costs. Sorry, Rage Extractor!
- 9 September 2022You may only pay the additional cost once per permanent spell.