Understanding the lore abilities of The Long Reach of Night

I'm building a deck and have been looking at [[The Long Reach of Night]], and I'm wondering specifically how the I and II effects work:

I, II — Each opponent sacrifices a creature of their choice unless they discard a card.

To me, it reads as a faces a villainous choice-like effect and I'm aware of the Villainous Choice ruling wherein a player can choose to do one of the options (i.e. Discard a card) when it is impossible to do so (that player has no cards in hand) and I'm wondering if this is similar.

Scenario: Player A casts The Long Reach of Night, Lore ability I activates. Player B has cards in hand, but no creatures to sacrifice.

Would Player B be forced to discard, or can they choose to sac a creature, despite not having a creature on the field?

Scenario: Lore ability II activates before Player A's Draw. Player B has no cards in hand and an Elvish Mystic on the field.

In this case, would I be correct in that Player B would have no choice but to sack their Mystic?