Blood on the Snow

• WWizards of the Coast2021-02-05
  Official Ruling
  If Blood on the Snow is copied, no mana was spent to cast the copy, so you can return only a creature or planeswalker card with mana value 0.
• WWizards of the Coast2021-02-05
  Official Ruling
  You choose a mode for Blood on the Snow as you cast it. The last part of the effect (returning a card to the battlefield) happens no matter which mode you choose.
• WWizards of the Coast2021-02-05
  Official Ruling
  If you cast Blood on the Snow without spending snow mana, you can return only a creature or planeswalker card with mana value 0. (Planeswalker cards with mana value 0 likely not coming soon.)
• WWizards of the Coast2021-02-05
  Official Ruling
  Snow is a supertype, not a card type. It has no rules meaning or function by itself, but spells and abilities may refer to it.
• WWizards of the Coast2021-02-05
  Official Ruling
  The symbol is a generic mana symbol. It represents a cost that can be paid by one mana that was produced by a snow source. That mana can be any color or colorless.
• WWizards of the Coast2021-02-05
  Official Ruling
  Snow isn’t a type of mana. If an effect says you may spend mana as though it were any type, you can’t pay for using mana that wasn’t produced by a snow source.
• WWizards of the Coast2021-02-05
  Official Ruling
  Blood on the Snow doesn’t target any creature or planeswalker card in your graveyard. You choose which one to return to the battlefield, if any, as Blood on the Snow resolves. Notably, you could return one of the creatures or planeswalkers that was just destroyed by Blood on the Snow.
• WWizards of the Coast2021-02-05
  Official Ruling
  The Kaldheim set doesn’t have any cards with mana costs that include , but some previous sets do. If an effect says such a spell costs less to cast, that reduction doesn’t apply to any costs. This is also true for activated abilities that include in their activation costs and effects that reduce those costs.
• WWizards of the Coast2021-02-05
  Official Ruling
  Some cards have additional effects for each spent to cast them. You can cast these spells even if you don’t spend any snow mana to cast them; their additional effects simply won’t do anything.
• WWizards of the Coast2021-02-05
  Official Ruling
  If a card in a graveyard has in its mana cost, X is considered to be 0.

Rulings via Scryfall