Cheapest priced copy (Commander 2016): $4.99 at Card Kingdom, near mint, their price list as of .
Coastal Breach 
Sorcery · Rare · Commander 2016 · #6
Undaunted (This spell costs {1} less to cast for each opponent.)
Return all nonland permanents to their owners' hands.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $4.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2016 | 6 | Rare | $4.99 | — |
2 rulings from Wizards of the Coast
- 8 November 2016Effects that reduce what you pay to cast a spell don’t affect its mana value.
- 8 November 2016Causing an opponent to lose the game after you’ve announced that you’re casting a spell with undaunted and determined its total cost won’t cause you to have to pay more mana.