Riki + Venomancer

Why this works

Picking these two together is a bet on overwhelming damage and slows instead of hard lockdown. Venomancer can make it incredibly difficult for an enemy to escape Riki. A good Venomous Gale or even the constant slow from Poison Sting lets Riki stay on a target’s back to secure a kill. The combination of Poison Nova softening up an entire team for Riki's Tricks of the Trade can also be fight-winning. The major weakness is the shared lack of a real stun. Against heroes with instant escapes or important channeling spells, this duo has no reliable way to interrupt them.

Your game plan is to force fights where your area damage can't be avoided. In the mid-game, you’ll look for a big Poison Nova, then have Riki drop Smoke Screen on the enemy backline to start picking off supports. The enemy team knows this is coming. Their goal is to spread out to minimize the impact of your spells and to itemize for saves and magic resistance. They want to survive the initial burst, then turn and kill either Venomancer or Riki, who can both be fragile if caught out of position.