Stronghold the Moving Fortress
Trap Card
After activatation, Special Summon this card in Defense Position; it is treated as an Effect Monster Card (Machine-Type/EARTH/Level 4/ATK 0/DEF 2000). (This card is still treated as a Trap Card.) While "Green Gadget", "Red Gadget", and "Yellow Gadget" are all face-up on your side of the field, the ATK of this card becomes 3000.

4/5 for me. Pretty good and a nice defense when you need one.