Make Illaoi's passive a charge/clickable system.
She can right click on a wall to summon a tentacle there after a short delay (say 1 second.) With maybe max 2 charges at a time? Obviously refilling on the current CD. However, she can't summon/place tentacles while in combat or they take significantly longer to appear as to prevent her from just chasing people and summoning tentacles in front of them.
This will give her control over where her tentacles can be and open up the jungle to her. Instead of a scenario of "Oh, my tentacle spawned at the inner turret and we're still laning at the outer turrets."