Yes, you counted right. Five Synchro Monsters at once.
Yusei pulls a similarly awesome move, summoning 3 Synchro Monsters with 1 combo about 15 chapters earlier.
Paradox gets one in the first chapter of Redeem Us. Yusei has already summoned Saviour Star Dragon, on his first turn no less, a card which has spelled doom for countless opponents before; and not only does it do nothing to stop Paradox, he bests it in one turn, with one straight-up attack.
