Cheapest priced copy (The Lord of the Rings: Tales of Middle-earth): $0.49 at Card Kingdom, near mint, their price list as of .
Isildur's Fateful Strike 
Legendary Instant · Rare · The Lord of the Rings: Tales of Middle-earth · #542
(You may cast a legendary instant only if you control a legendary creature or planeswalker.)
Destroy target creature. If its controller has more than four cards in hand, they exile cards from their hand equal to the difference.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
5 printings · $0.49 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The Lord of the Rings: Tales of Middle-earth | 91 | Rare | $0.49 | $0.49 |
| The Lord of the Rings: Tales of Middle-earth | 356 | Rare | $0.59 | — |
| The Lord of the Rings: Tales of Middle-earth | 542 | Rare | $1.99 | $1.99 |
| The Lord of the Rings: Tales of Middle-earth | 767 | Rare | — | $0.49 |
| Tales of Middle-earth Promos | 91s | Rare | — | $1.29 |
3 rulings from Wizards of the Coast
- 16 June 2023Isildur's Fateful Strike is the first legendary instant. It is subject to the same casting restrictions as existing legendary sorceries, as listed in the following rulings.
- 16 June 2023You can't cast a legendary instant unless you control a legendary creature or a legendary planeswalker. Once you begin to cast a legendary instant, losing control of your legendary creatures and planeswalkers won't affect that spell.
- 16 June 2023Other than the casting restriction, the legendary supertype on an instant carries no additional rules. You may cast any number of legendary instants in a turn, and your deck may contain any number of legendary cards (but no more than four of any with the same name).