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

Relevant cards

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