Stronghold the Moving Fortress [SDGR-EN030] Common

Special Summon this card in Defense Position as an Effect Monster (Machine-Type/EARTH/Level 4/ATK 0/DEF 2000). (This card is still treated as a Trap Card.) While you control a "Green Gadget", "Red Gadget", and "Yellow Gadget" , this card gains 3000 ATK.