Cheapest priced copy (Streets of New Capenna): $0.35 at Card Kingdom, near mint, their price list as of .
Grisly Sigil 
Sorcery · Uncommon · Streets of New Capenna · #82
Casualty 1 (As you cast this spell, you may sacrifice a creature with power 1 or greater. When you do, copy this spell and you may choose a new target for the copy.)
Choose target creature or planeswalker. If it was dealt noncombat damage this turn, Grisly Sigil deals 3 damage to it and you gain 3 life. Otherwise, Grisly Sigil deals 1 damage to it and you gain 1 life.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Streets of New Capenna | 82 | Uncommon | $0.35 | $0.49 |
5 rulings from Wizards of the Coast
- 29 April 2022If you cast Grisly Sigil targeting a creature or planeswalker that hasn't been dealt noncombat damage this turn, choose to pay its casualty cost, and choose not to change the target, the copy will deal 1 damage and you will gain 1 life. Then, the original spell will resolve. It will deal 3 damage, and you will gain 3 life.
- 29 April 2022Casualty N means “As an additional cost to cast this spell, you may sacrifice a creature with power N or greater.” and “When you cast this spell, if a casualty cost was paid for it, copy it. If the spell has any targets, you may choose new targets for the copy.”
- 29 April 2022The copy of the spell is created on the stack, so it's not “cast.” Abilities that trigger when a player casts a spell won't trigger.
- 29 April 2022If you pay the casualty cost of a spell, the copy will resolve before the original spell.
- 29 April 2022You may sacrifice only one creature to pay a spell's casualty cost, and you copy the spell only once.