If a Level 10 EARTH Machine-Type monster(s) is Normal or Special Summoned to your field (except during the Damage Step): You can activate this effect; your opponent takes no battle damage for the rest of this turn (even if this card leaves the field), also you Special Summon 1 Level 4 EARTH Machine-Type monster with 1800 or more ATK from your Deck, and if you do, it becomes Level 10. You can send 1 card from your hand to the GY; add 1 Level 10 EARTH Machine-Type monster from your Deck to your hand. You can only use 1 "Revolving Switchyard" effect per turn, and only once that turn.