Lissandra new passive

This passive idea hit me and i wanted to know if anyone else think its good so here it is:

Dark ice: every 15 seconds 1/2/3 corrupted ice pillars spawn randomly near lissandra ( radius is something like zyras plant spawn one ). enemy champions that walk over the pillars destroy them. If lissandra comes to contact with one pilar she gains 8/16/24% of her missing mana, if lissandra hits ice pillar with ability all her cooldowns are reduced by 8 seconds ( ult excluded ) and she gains short boost of movement speed.

so i think this would be good since it would still be a passive that gives mana but if lissandra wants it she can use it to go in without having to be afraid of getting stomped since her only engage tool is e, she can destroy a pillar if its there and that would refresh her q,w,e and she can finish the enemy and e back to safe distance