Heim fix suggestion...

Replace his passive with "Entrenched", Each active turret nearby grants X Health regen to allied champions and turrets. Each active turret in range of another grants Y Armor and MR to each other turret. With 2 turrets in range of each other, AoE damage is reduced by Z%. (Turrets lose benefits when deactivated.)

I'm not a numbers whiz on how well this would work... but I dunno, could be a fix.