This is a good card, but one that requires being used in a specially-prepared deck - preferably a deck loaded with sorcery and instant cards for dealing damage, as opposed to lots of creatures
This is quite easily abusable with Treasure tokens especially, but it doesnt end there
Sure, it's just Dragons it recurs, but that's the most played kindred creature type in casual, so you have loads of options, plus the first Bladewing too in Red and Kokusho, the Evening Star in Black
So what are these serialized cards
Three mana is a tad on the expensive side given that you also need to pay the cost of the spell you flashback, but its still doable
Of the five experience counter generals on display this week, Mizzix of the Izmagnus might be the most broken and still be the best design