Phantom Lancer + Wraith King

Why this works

Putting two hard carries on the same team can be a liability, but this duo works because of how directly they support each other. Wraith King provides a simple, reliable frontline with a stun, and his Reincarnation forces opponents to commit massive resources to kill him once, let alone twice. All that time and chaos is exactly what Phantom Lancer needs to build his own army of illusions. On top of that, Wraith King's lifesteal aura benefits every one of Phantom Lancer's illusions, making them surprisingly durable and allowing them to sustain through long engagements.

This creates an unsolvable problem for the enemy team in fights. If they focus on bursting down Wraith King, they have to deal with his second life while Phantom Lancer and his copies are hitting them freely. If they try to go on the slippery Phantom Lancer instead, they turn their back on a heavy-hitting carry who can stun them for it. Drafting enough area damage to handle the illusions often leaves a team without the single-target burst needed to deal with Wraith King, so they are always unprepared for one threat or the other.