Cheapest priced copy (Gatecrash): $0.35 at Card Kingdom, near mint, their price list as of .
Knight of Obligation 
Creature — Human Knight · 2/4 · Uncommon · Gatecrash · #18
Vigilance
Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Gatecrash | 18 | Uncommon | $0.35 | $0.79 |
4 rulings from Wizards of the Coast
- 12 January 2024The amount of life you gain from extort is based on the total amount of life lost, not necessarily the number of opponents you have. For example, if your opponent's life total can't change (perhaps because that player controls Platinum Emperion), you won't gain any life.
- 12 January 2024The extort ability resolves before the spell that caused it to trigger. The ability resolves even if that spell is countered.
- 12 January 2024You may pay {W/B} a maximum of one time for each extort triggered ability. You decide whether to pay when the ability resolves.
- 12 January 2024The extort ability doesn't target any player.