Cheapest priced copy (Journey into Nyx): $0.35 at Card Kingdom, near mint, their price list as of .
Goldenhide Ox 
Enchantment Creature — Ox · 5/4 · Uncommon · Journey into Nyx · #125
Constellation — Whenever this creature or another enchantment you control enters, target creature must be blocked this turn if able.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Journey into Nyx | 125 | Uncommon | $0.35 | $0.49 |
6 rulings from Wizards of the Coast
- 26 April 2014If multiple attacking creatures must be blocked if able, the defending player must assign at least one blocker to each of them if possible. For example, if two such creatures were attacking and there were two potential blockers, they couldn't both be assigned to block the same attacker.
- 26 April 2014The constellation ability doesn't force any specific creature to block the target creature.
- 26 April 2014An Aura spell without bestow that has an illegal target when it tries to resolve won't resolve and will be put into its owner's graveyard. It won't enter the battlefield and constellation abilities won't trigger. An Aura spell with bestow won't be countered this way. It will revert to being an enchantment creature and resolve, entering the battlefield and triggering constellation abilities.
- 26 April 2014The defending player must assign at least one blocker to the target creature during the declare blockers step if that player controls any creatures that could block it.
- 26 April 2014A constellation ability triggers whenever an enchantment enters the battlefield under your control for any reason. Enchantments with other card types, such as enchantment creatures, will also cause constellation abilities to trigger.
- 26 April 2014When an enchantment enters the battlefield under your control, each constellation ability of permanents you control will trigger. You can put these abilities on the stack in any order. The last ability you put on the stack will be the first one that resolves.