There's more to doing Malygos in 5 minutes than just "stack as many sparks as you can and hope" (in fact, you explicitly do *not* want to stack as many sparks as you can.) How to do "You Don't Have An Eternity"....:
We found it far easier when we thought about the timing and realized we didn't just want to stack as many sparks as our raid could handle, there actually is a specific number you want to stack.