Blood on the Snow

The {S} 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.

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 {S} using mana that wasn’t produced by a snow source.

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.

The Kaldheim set doesn’t have any cards with mana costs that include {S}, but some previous sets do. If an effect says such a spell costs {1} less to cast, that reduction doesn’t apply to any {S} costs. This is also true for activated abilities that include {S} in their activation costs and effects that reduce those costs.

Some cards have additional effects for each {S} 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.

If a card in a graveyard has {X} in its mana cost, X is considered to be 0.