Rattle Bones (Red)

Banish target Runeblade attack action card from your graveyard. You may play it this turn.

If you've dealt arcane damage to an opponent this turn, you may play this as though it were an instant.

Go again

Rulings

From the Crucible of War release notes

If this is played as though it were an instant, it would not cost an action point but when it resolves you would gain an action point from go again (as long as it’s your action phase)
If the attack action card is played, it would go to the graveyard afterwards (Unless an effect tells you otherwise).
If the attack action is not played, it would remain in the banished zone.

Keyword notes

Go again - Go again allows multiple actions to be played in a turn when usually playing an action with use up your action point, and therefore end your turn. A card with go again gives the controller of that card or activated ability 1 action point when it resolves.

When an action with go again resolves, its controller gains 1 action point.
Multiple instances of go again on the same card or activated ability do not stack. If a card or activated ability has multiple instances of go again when it resolves its controller gains 1 action point only.
If an action with go again does not resolve, its controller does not gain 1 action point.
You cannot reveal a card with no to Belittle. The card must have a value to its power that is 3 or less. (0 is a value)