Narfi, Betrayer King

Another snow Zombie creature you control will get only +1/+1 from Narfi's first ability.

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

Some cards have additional effects for each snow mana 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.