Make his wall able to block skillshoots. This will make him viable against poke compositions.
It will also add a bit realism and utility. it´s better to add a bit of utility than buffing numbers that can lead to a huge power change.
Skillshoots like Dark binding, Javelin Toss, Mystic Shot, Electro harpoon, Bandage Toss, Enchanted Crystal Arrow, Rocket Grab, Sear , 90 Caliber Net , Missile Barrage, Infected Cleaver, Chum the Waters, Thundering Shuriken, Ethereal Chains, Light Binding, Sonic Wave , Dredge Line , Glacial Prison , Acid Hunter , Bouncing Bomb .
The idea is that the wall will have a hitbox that work the same way as a players hitbox.
Skills like Light Binding only loses the first hit.
Skillshoots with splash will deal damage around the point where it hit the wall.
Skills like Sonic Wave and Bandage Toss should pull you to the wall.
I believe this would fit the troll perfectly. It will make the game more exciting and fun to watch.
Saving your teammates feels great and rewarding. Right now his wall doesn´t feal right, because a lot of heroes have flash, dashes and movement steroids.