How to balance Taliyah and give her unique niche

As we all know, Taliyah is much better after buffs, but she lacks utility if dhe has to be roaming control mage. Also, there is problem with her W, which is basically unusable on its own, only in conjunction with E. What i propose is this: If Taliyah uses her W without giving it direction (only one use), it leaves the rock behind, blocking movement, just as Trundle's pillar. However, this terrain is lasts indefinitely, unless she uses directionless W again or dies. This would give her power to seal narrow chokes, allow her to support champions who require terrain (vayne, bard, poppy) She could be somewhat safer in mid lane, considering she can close one of 8 mid lane enterances and play around that

Is it too strong?