Try:

Code:
/castsequence Flame Shock, Lavaburst,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, Lava Burst,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
/cast Lightning Bolt
Macro will cast Flame Shock>Lavaburst>LB>LB>LB etc, Lavaburst>More LBs> repeat.