Death's Decree with beam attacks

[Magnetowasright]

Vision targets a character with his beam attack and an allied Thanos uses Death's Decree.  If there's multiple enemies under the beam template do all attack rolls get the bonus attack dice or just against the original declared target or against any target under the beam template?

[Negoldar]

Targets aren’t declared normally for beam attacks. Don’t declare a target then place the template. Put the template down and see who the targets are then start doing a series of attacks—one for each character contacting or overlapping the template. 

Each target will work through the timing chart including step 2d which is the step when Thanos’s Death’s Decree is used. 

It will affect the character you are currently attacking and no others. It can be used once per turn so it can’t be used again to add dice any of the other attacks in the beam.