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Here's one way to make multiple toggles activate with one key.

/bind <key> "+ $$powexec_toggleon Combat Jumping$$powexec_toggleon Fire Shield"

What that will do is on the down press it will activate fire shield and on the release (if it's held long enough) it will activate combat jumping. You can use as many toggleons as you want, more than two will require multiple keypresses.

/bind <key> "powexec_toggleon combat jumping$$powexec_toggleon fire shield$$powexec_toggleon fiery aura"