Konami thought that giving Quintet Magician the effect "on fusion summon play a free 'Raigeki' and 'Harpie's feather duster' from out of your deck" was balanced.
It's easy to use this effect two times with polymerization on the 4th/5th turn, followed by magicalized fusion if you are still alive.
I somehow survived this and won because the free "Raigeki" + "Harpie Feather" activated only during the first fusion summon.
The guy banished the wrong monsters maybe.