Complex sentence: Using its second ability to attack twice, Jaden slays both Malefic versions of R.D. and C.E.D. Yubel congradulates Jaden and remarks she's heard of dragon slaying, but not two at the same time.
Split into simpler sentences: Using its second ability to attack twice, Jaden slays both Malefic versions of Rainbow Dragon and Cyber End Dragon. Yubel commends Jaden and remarks that she had heard of dragon slaying, but not two at the same time.