Show: All formats Goat Perfect Circle Edison
Discarding is not a cost.
Discard all the cards in your hand, then select a number of LIGHT monsters in your GY equal to the number of cards you discarded, and add them to your hand.
"Beckoning Light" doesn't target.
You CANNOT activate Beckoning Light if there are fewer LIGHT monsters in your GY than there are cards in your hand, even if 1 or more of the cards in your hand are LIGHT monsters.
When you resolve "Beckoning Light", first discard, then pick cards to add to your hand. So you can add cards to your hand that you discarded while resolving "Beckoning Light".
You can activate Beckoning Light while Macro Cosmos is active, but since no cards will be discarded to the GY, you CANNOT add any LIGHT monsters from your GY to your hand [REF].
If you don't have enough LIGHT monsters as there are cards in your hand, you cannot activate "Beckoning Light".
If Disappear is chained, and there are now fewer LIGHT monsters in your GY than cards in your hand, Beckoning Light resolves without effect (you don't discard your hand or add cards to your hand).
You cannot activate "Beckoning Light" if you have no cards in your hand.
If your opponent chains "Disappear" to "Beckoning Light", and there are no longer enough LIGHT monsters to retrieve as there were cards in your hand, the effect of "Beckoning Light" disappears and you don't discard your hand or add cards to your hand.