Invoker + Keeper of the Light

Why this works

Facing this pair often feels like a battle of attrition you can't win. Keeper of the Light can use Chakra Magic to solve Invoker's constant mana problems, letting him play at a much higher tempo. Instead of saving mana for a big combo, the Invoker can afford to use spells constantly for farming, harassing, and lane control. An Invoker who can throw out a Tornado and EMP on a creep wave and be at full mana moments later is a huge problem. It allows him to accelerate his levels and item timings far more than he normally could, building an early advantage through resource superiority.

This pressure continues into the mid-game, where the two can effectively siege and control the map. Keeper of the Light pushes lanes out with Illuminate, while a fully-supplied Invoker is free to rotate or use global spells to punish any reaction. The main weakness of this strategy is that both heroes are quite vulnerable. They don't provide much to save each other if they're initiated on by mobile heroes. Coordinated aggression can shut them down before their spell-based pressure takes over the game, which is why their success together often hangs on a knife's edge.