I would expect this to be an uncommon. You need to hit an instant or a card with flash with that etb effect to be able to play it btw. That kinda puts flash into question. Why does a red common have flash anyway? Isn't the keyword primarily in sultai colors?

I though flash was in esper?

Strangely enough flash isn't supposedly in anymore than its in (mechanical color pie article). Personally I feel that it should be though as it naturally creeps into white (uncommon) slots.