Q: If several abilities are triggered at the same time (at the start
of a hero phase, for example), how do you determine the order in
which they are used?
A: If several abilities can be used at the same time, the
player whose turn is taking place uses their abilities
first, one after the other, in any order they desire; then
the player whose turn is not taking place uses their
abilities, one after another, in any order they desire.
The same principle applies to any other things – such as
command traits or artefacts of power – that can be used
simultaneously. Note that abilities used at the start or
the end of a phase still count as being used in the phase
in question.