Got Merciless Eviction from a booster, and it states that you can choose one and then exile all artifacts, creatures, enchantments or planeswalkers. Does this mean that all instances in graveyards and in players' decks actually get removed as well as cards on the battlefield?
Unless the rules text specifically mentions cards in another zone, only permanents (cards on the battlefield and tokens) are affected by spells and effects.
109.2. If a spell or ability uses a description of an object that includes a card type or subtype, but doesn't include the word "card," "spell," "source," or "scheme," it means a permanent of that card type or subtype on the battlefield.