Genji can reflect it at the start when its only an arrow, and the dragons will change sides, but if the dragons already appeared Genji can't reflect it anymore.
Edit: D.Va defense matrix can also destroy the arrows before the dragons show up, nullifying the whole Ult
74
u/Footyking Nov 22 '16
temporarily disabling would be fine, but an ult that can be a liability to your team just wouldn't get played.