Reverberate | Dual Strike

Cards

You have a way to cast an additional instant or sorcery, or an opponent is casting one.

({R} magic symbol) ({R} magic symbol) ({R} magic symbol) , plus an additional ({R} magic symbol) if
Dual Strike was not foretold, plus enough mana to cast the additional spell if needed available.

Cast any other instant and/or sorcery spell, or wait for an opponent to cast one.
Holding priority, cast
Dual Strike by paying ({R} magic symbol) ({R} magic symbol) , copying the next instant or sorcery spell you cast with mana value four or less.
Cast
Reverberate by paying ({R} magic symbol) ({R} magic symbol) , targeting the instant or sorcery spell cast in step 1.
Dual Strike triggers, copying
Reverberate, with the copy targeting the original
Reverberate.
Resolve the copy of
Reverberate, copying
Reverberate, with the copy targeting the original
Reverberate.
Repeat step 5.