FOILCheapest priced copy (Commander Legends): $0.49 at Card Kingdom, near mint, their price list as of .
Shipbreaker Kraken 
Creature — Kraken · 6/6 · Rare · Theros Promos · #63★
{6}{U}{U}: Monstrosity 4. (If this creature isn't monstrous, put four +1/+1 counters on it and it becomes monstrous.)
When this creature becomes monstrous, tap up to four target creatures. Those creatures don't untap during their controllers' untap steps for as long as you control this creature.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $0.49 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Legends | 404 | Rare | $0.49 | — |
| Theros Promos | 63★ | Rare | — | $0.79 |
| Theros | 63 | Rare | $0.49 | $0.49 |
7 rulings from Wizards of the Coast
- 15 September 2013An ability that triggers when a creature becomes monstrous won't trigger if that creature isn't on the battlefield when its monstrosity ability resolves.
- 15 September 2013If you lose control of Shipbreaker Kraken between when its last ability triggers and when that ability resolves, the target creatures will become tapped. However, they won't be affected by the other effect and will untap as normal during their controllers' untap steps.
- 15 September 2013Monstrous isn't an ability that a creature has. It's just something true about that creature. If the creature stops being a creature or loses its abilities, it will continue to be monstrous.
- 15 September 2013If another player gains control of Shipbreaker Kraken, the creatures will no longer be affected by the effect preventing them from untapping, even if you later regain control of Shipbreaker Kraken.
- 15 September 2013If you gain control of a creature that's being prevented from untapping, that creature won't untap during your untap step for as long as you control Shipbreaker Kraken.
- 15 September 2013The ability can target a tapped creature. If a targeted creature is already tapped when it resolves, that creature just remains tapped and doesn't untap during its controller's untap step.
- 15 September 2013Once a creature becomes monstrous, it can't become monstrous again. If the creature is already monstrous when the monstrosity ability resolves, nothing happens.