Icy Aura
As long as Mamoswine is your Active Pokémon, put 1 damage counter on each Active Pokémon (excluding Pokémon)(both yours and your opponent's) between turns.
Avalanche
Flip a coin. If heads, this attack does 10 damage to each of your opponent's Benched Pokémon. (Don't apply Weakness and Resistance for Benched Pokémon.)