Blizzard Brawl

• WOTC Official Reminder Textofficial rules
  Fight — Each of those creatures deals damage equal to its power to the other.

• WWizards of the Coast2021-02-05
  Official Ruling
  You can’t cast Blizzard Brawl unless you choose both a creature you control and one you don’t control as targets.
• 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
  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
  If either target is an illegal target as Blizzard Brawl tries to resolve, neither creature will fight and no damage will be dealt.
• WWizards of the Coast2021-02-05
  Official Ruling
  If the creature you control is still a legal target as Blizzard Brawl tries to resolve but the target creature you don’t control isn’t, the creature you control will still get the bonuses until end of turn.
• WWizards of the Coast2021-02-05
  Official Ruling
  Check whether you control three or more snow permanents as Blizzard Brawl is resolving to see if the target creature you control gets +1/+0 and gains indestructible. That creature will still fight even if it doesn’t get those bonuses.
• 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
  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.

Rulings via Scryfall