Cheapest priced copy (Guilds of Ravnica): $0.99 at Card Kingdom, near mint, their price list as of .
Nullhide Ferox 
Creature — Beast · 6/6 · Mythic · Guilds of Ravnica · #138
Hexproof
You can't cast noncreature spells.
{2}: This creature loses all abilities until end of turn. Any player may activate this ability.
If a spell or ability an opponent controls causes you to discard this card, put it onto the battlefield instead of putting it into your graveyard.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Guilds of Ravnica | 138 | Mythic | $0.99 | $0.99 |
| The List | GRN-138 | Mythic | $0.99 | — |
3 rulings from Wizards of the Coast
- 5 October 2018Once Nullhide Ferox's activated ability has resolved, it can gain new abilities. It won't lose those abilities.
- 5 October 2018Nullhide Ferox's activated ability can be activated only while it's on the battlefield. Players can't, for example, activate it to try to stop its replacement effect from putting it onto the battlefield.
- 5 October 2018Once Nullhide Ferox has lost its activated ability that makes it lose its abilities, that ability can't be activated again until the turn's over.