Juggernaut + Io

Why this works

Picking a carry to pair with Io usually involves finding a hero who loves the extra attack speed and survivability. The issue with Juggernaut is that his most important abilities create moments where Io can't help him. During Blade Fury, Juggernaut is unable to attack, making the bonus from Overcharge worthless. When he uses Omnislash, he's already invulnerable and untargetable, so Io’s defensive support becomes redundant. Instead of amplifying his strengths, Io's spells often find Juggernaut in a state where he can't benefit from them, leading to an awkward and inefficient pairing.

The lane itself might feel fine, using Tether's movement speed to set up a good spin. The trouble starts when the duo tries to make plays around the map. A Relocate gank can go sour if Omnislash doesn't immediately kill the target, leaving Juggernaut stranded. In teamfights, Juggernaut either uses his ultimate and leaves Io behind, or he tries to right-click with Overcharge but stays vulnerable to stuns. Since Juggernaut also has his own sustain with Healing Ward, the constant regeneration from Io feels less critical than it does for other cores.