Cheapest priced copy (Core Set 2019): $0.35 at Card Kingdom, near mint, their price list as of .
Frilled Sea Serpent 
Creature — Serpent · 4/6 · Common · The List · #M19-56
{5}{U}{U}: This creature can't be blocked this turn.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Core Set 2019 | 56 | Common | $0.35 | $0.49 |
| Core Set 2020 | 61 | Common | $0.35 | $0.49 |
| The List | M19-56 | Common | $0.35 | — |
One ruling from Wizards of the Coast
- 12 July 2019Once Frilled Sea Serpent has been blocked, activating its ability won't change or undo that block.