Would the two Basic energy cards attached by Terrakion EX's "Pump-up Smash" attack trigger Ampharos' "Electromagnetic Wall" Ability twice or only once (or not at all)?
Any energies attached from the hand would trigger Electromagnetic Wall, once for each energy card being attached.
Source: Dragons Exalted FAQ (2012-08-23), TPCi Rules Team (2012-08-23)

Relevant cards

Note: All applicable cards may not be listed below.
BW6_40