I have an Agent of the Fates in my graveyard. I return it to my hand with Disentomb.
Does my opponent have to sacrifice a creature?
No. The Heroic ability only works if the creature you target is a permanent on the battlefield. Most abilities only work from the battlefield. From rule 112.6:
112.6. Abilities of an instant or sorcery spell usually function only while that object is on the stack. Abilities of all other objects usually function only while that object is on the battlefield. The exceptions are as follows:
There's a few exceptions, but the ones regarding activated or triggered abilities are i and j. They're quoted in full below. The basic gist of these exceptions, and rule 112.6, is that no activated or triggered abilities work outside the battlefield — unless it involves a cost or trigger condition that can't work on the battlefield, in which case it works wherever it can work.
A good example of these exceptions (specifically exception i) is Scavenge or Bloodrush. The former requires you to exile the card from your graveyard, and the latter requires you to discard it (and cards can only be discarded from your hand, nowhere else). Since those costs can only be paid somewhere outside the battlefield, Scavenge works inside your graveyard, and Bloodrush works inside your hand. (But that's the only places they work, since their costs can't be paid anywhere else.)
Since Heroic works just fine on the battlefield, though, it isn't covered by these exceptions (specifically the one regarding triggered abilities, exception j) and doesn't get to work elsewhere too.
112.6i An objects activated ability that has a cost that can't be paid while the object is on the battlefield functions from any zone in which its cost can be paid.
112.6j A trigger condition that can't trigger from the battlefield functions in all zones it can trigger from. Other trigger conditions of the same triggered ability may function in different zones.
Example: Absolver Thrull has the ability "When Absolver Thrull enters the battlefield or the creature it haunts dies, destroy target enchantment." The first trigger condition functions from the battlefield and the second trigger condition functions from the exile zone. (See rule 702.54, "Haunt.")
answered Jul 20 '14 at 13:21
-
I think the golden rule of magic is more relevant here. 101.1. Whenever a card's text directly contradicts these rules, the card takes precedence. Some cards specifically say you can activate the ability only from a specific zone (usually the graveyard), and so their rule takes precedence. – Rainbolt Jul 20 '14 at 19:22
-
2@Rainbolt The explanation I've provided is what got me understanding it when I was new. 101.1 doesn't make sense here, because the card doesn't contradict the rules - it doesn't have anything saying "this works in the graveyard" or "this works in your hand". Without 112.6 and its exceptions, some abilities just appear like some idiot wrote an ability that can't possibly work. – doppelgreener Jul 20 '14 at 22:44
-
@Rainbolt, Jonathan Hobbs's assessment of why 101.1 doesn't apply is completely correct. – ikegami Jul 21 '14 at 0:38
-
1@LuisMasuelli Not really. If "Exile this card from your graveyard:" is the cost, that doesn't actually state that you can pay this effect while the card is in the graveyard, any more than you can tap a mana elf while it's in the graveyard. 112.6 solves this problem. Otherwise it would be argued that Elder of Laurels says you can pay mana to pump your creatures, and thus by 101.1, you can do that anywhere (after all, the card doesn't state that this is only true for cards on the battlefield, and if card "always beats the rules"...) – deworde Jul 21 '14 at 12:11
-
2What @deworde said is precisely it. Pretty sure 101.1 is more applicable as the foundation of cards like Platinum Angel. – doppelgreener Jul 21 '14 at 12:12
