Cheapest priced copy (Forgotten Realms Commander): $4.99 at Card Kingdom, near mint, their price list as of .
Klauth's Will 
Instant · Rare · Forgotten Realms Commander · #51
Choose one. If you control a commander as you cast this spell, you may choose both instead.
• Breathe Flame — Klauth's Will deals X damage to each creature without flying.
• Smash Relics — Destroy up to X target artifacts and/or enchantments.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $4.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Forgotten Realms Commander | 51 | Rare | $4.99 | — |
| Forgotten Realms Commander | 321 | Rare | $4.99 | — |
3 rulings from Wizards of the Coast
- 23 July 2021Once you've announced that you're casting Klauth's Will, players can't take any actions until you've finished doing so. Notably, opponents can't try to remove your commander to change how many modes you may choose.
- 23 July 2021The commander you control doesn't have to be your commander.
- 23 July 2021Whether or not you control a commander is determined only once, as you choose the modes for this spell. If you somehow lose control of that commander before you finish casting the spell (perhaps because you sacrifice it to activate a mana ability), it won't change the number of modes chosen.