Heartstone WOULD reduce the cost of bringing back Reassembling Skeleton from the graveyard, but Training Grounds would NOT because you do not control creatures in your graveyard, is that correct?
109.2. If a spell or ability uses a description of an object that includes a card type or subtype, but
doesn’t include the word “card,” “spell,” “source,” or “scheme,” it means a permanent of that card
type or subtype on the battlefield.
but Training Grounds would NOT because you do not control creatures in your graveyard, is that correct?
And in your graveyard it's not a "creature", although it might be a "creature card".
109.2a If a spell or ability uses a description of an object that includes the word “card” and the
name of a zone, it means a card matching that description in the stated zone.
Private Mod Note
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Rollback Post to RevisionRollBack
Why bother with mere rulings when so many answers can be found in the Rules?
No, it's not on the battlefield.
And in your graveyard it's not a "creature", although it might be a "creature card".
RULES OF MAGIC :
http://magic.wizards.com/en/game-info/gameplay/rules-and-formats/rules