It won't be op with fractal at all. It'll be on par with giant frog. The unupped version has the same attack as frog, so it's exactly as OP(UP?) as fractal frogs, and for only one turn, and the upped version costs 50% more for slightly less than 50% more damage than frogs. You'll get pillars after, but you'll also lose your attackers on any subsequent turns. If you're going for an otk, the only advantage over frogs is a slightly higher burst damage; if you're going for more long term damage, it has a disadvantage over frogs.
For another fractal comparison, compare it to ball lightnings(spark). You get +2 damage per attacker over both versions with this card. You also get +2/+3 quanta cost with this card, which will be recouped over 2 turns. You need a higher quanta investment than fractal spark/balls, but you'll get it back eventually, if you don't make the kill right away. That could let you more easily pay for the next fractal treant burst, but the next spark/ball burst doen't -need- paying for, other than the fractal itself. Also, ball lightnings will trigger death effects like bone wall or soulcatcher, which is often done with such a deck, whereas treants will not. (or at least they shouldn't, based on that wording)
The way I look at this card is more like a fractalable lightning bolt that only works on players and leaves a pillar behind. (and has shield counters, but then so do lightning bolts) Or I look at it as a slower version of a pillar that deals damage when played.
