x2Ride of the High KingThis attack does 30 more damage for each of your opponent's Benched Pokémon.
Max LanceYou may discard up to 2 Energy from this Pokémon. If you do, this attack does 120 more damage for each card you discarded in this way.
Can I use Ice Rider Calyrex VMAX's "Max Lance" attack to discard 2 Double Colorless Energy cards?
Yes, you can select 1 Energy of each Double Colorless Energy to discard both of them. And it would do 240 more damage because you discarded 2 cards.
If I use Ice Rider Calyrex VMAX's "Max Lance" attack to discard a Double Colorless Energy, does it do 120 or 240 more damage?
The additional damage is done per each card discarded, so if you discard only one card it only does 120 more damage.
