Underlord + Clockwerk

Why this works

The setup seems obvious on paper: Clockwerk uses Hookshot and Power Cogs to trap a target, while Underlord lays down Pit of Malice and Firestorm for a guaranteed kill. This sequence is clunkier than it looks. Underlord has to be pre-positioned to contribute immediately, as his cast ranges are much shorter than Clockwerk's initiation. If he has to walk in, the target often gets a chance to use defensive items or abilities. The lockdown itself is somewhat redundant; a hero trapped in cogs doesn't benefit much from being rooted, and the combined damage over time isn't always enough to secure a kill before help arrives.

Across a game, this means their coordination often feels incidental rather than deliberate. They both want to be in the enemy's face, disrupting fights and being a nuisance, but they can end up doing so in different parts of the battle. Clockwerk will dive a backline hero, while Underlord is better at controlling the main frontline. The best-case scenario involves using Fiend's Gate to deliver Clockwerk for a surprise initiation, but this requires a level of coordination that isn't always present. Ultimately, they can function on the same team, but don't reliably amplify each other's plans.