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.
Source: TPCi Rules Team (2022-03-03)

Relevant cards

Note: All applicable cards may not be listed below.
SWSH6_46
SWSH6_46