Some AI3's like the rainbow could beat an all dragon mitosis and SOR deck. But then it did beat AI5's too.
Beating an AI3-5 -sometimes- is meh, try it in a tourney and let's see if it's OP. Also, I tried it with over 5 builds and none of them was enoughly fast. They only work well against
some stalls.
It's a 3-card vulnerable combo. If your dragon dies, bye combo, if you don't draw your dragon/SoR/Mitosis, bye combo, if you don't reach enough quanta to summon the dragon on time, bye combo. It's that simple, not OP, just a good combo once set up (as a quinted momentumed otyugh).