Block Dragon (Platinum Secret Rare)

Cannot be Normal Summoned/Set. Must be Special Summoned (from your hand or GY) by banishing 3 EARTH monsters from your hand and/or GY. Rock monsters you control cannot be destroyed, except by battle. If this card is sent from the field to the GY: You can add up to 3 Rock monsters from your Deck to your hand, whose total Levels equal 8. You can only use this effect of "Block Dragon" once per turn.