Alchemist + Io

Why this works

Tethering an ally is Io's core function, but it directly conflicts with Alchemist's game plan. Alchemist needs to farm solo to maximize Greevil's Greed and hit his item timings as fast as possible. Having Io in the lane or jungle with him slows down this acceleration by splitting experience, delaying the very advantage Alchemist is picked for. While the bonuses from Overcharge are useful once Alchemist has his items and is using Chemical Rage, the weakened early game often means he reaches that point too late to have the intended impact.

This pairing often struggles to find its footing. If Io stays with Alchemist, the carry's farm is slowed. If Io leaves to help other lanes, the two heroes aren't really playing together. Their primary coordinated move is a Relocate gank, but this is less effective than it seems. The enemy can see the Relocate destination and has time to react while Alchemist charges his Unstable Concoction. If that initial stun doesn't secure a kill, both heroes are left in a vulnerable spot with limited options.