yeah, after the change to the entropy shield, this is more powerful in mono-entropy than in a duo-trio-quarto, which was its intended use.
but i have a hard time believing people would be willing to pay 3 quanta for a tower, even paying 2 would seem high. i think front-loading the cost, and limiting the number that can come out is a much more realistic scenario, cost 3 [element] and can generate up to ~5 pillars/towers, one per turn per PQ, is much more workable.