If your opponent has 5 rearguards:
With the stride skill of Blaster Dark "Diablo", you choose one of your opponent's rearguards and retire it.
Call Deathspray Dragon and Fulbau "Diablo" in the back row.
Attack with Deathspray Dragon, with its skill, retire Fulbau "Diablo", and retire one of your opponent's rearguard. Use Fulbau's skill to call Blaster Dark Spirit. Retire one more. Do note to retire the back row.
If you have another Deathspray Dragon, use its skill to retire one more rearguard. Now, your opponent has only one left. You can activate the skill of Phantom Blaster "Diablo".