Does Wheel of Sun and Moon prevent cards from going to the graveyard from anywhere or just from the library?

Wheel of Sun and Moon has a replacement effect that reads: 'If a card would be put into enchanted player's graveyard from anywhere, instead that card is revealed and put on the bottom of that player's library.' The phrase 'from anywhere' is the critical wording — it covers all zones, not just the library.

Under CR 614.1, replacement effects modify what would happen to a game event. This effect intercepts any instance of a card going to that player's graveyard, regardless of whether the card came from the hand, battlefield, stack, exile, command zone, or library (CR 614.1a).

This means the enchanted player cannot mill, discard, sacrifice permanents to the graveyard, or have spells countered into the graveyard in the normal way — all of those cards instead go to the bottom of the library. Note that this applies only to cards; tokens that would go to the graveyard are unaffected by this replacement (they cease to exist instead, per CR 110.5g).

Concrete example: Your opponent controls Wheel of Sun and Moon enchanting you. You sacrifice your Elvish Mystic to pay a cost. Instead of going to your graveyard, Elvish Mystic is revealed and placed on the bottom of your library. Similarly, if Glimpse the Unthinkable mills you for 10, all 10 cards go to the bottom of your library one by one rather than your graveyard.

Because this is a replacement effect and not a triggered ability, it cannot be responded to — the card simply never touches the graveyard (CR 614.5).