Underlord + Lifestealer

Why this works

Using Fiend's Gate as a delivery system for an Infested Lifestealer is a classic and powerful combination. Underlord teleports himself and his passenger across the map for a sudden gank on an unsuspecting hero. Once they arrive, Underlord can immediately lock targets down with Pit of Malice, giving Lifestealer a perfect setup to emerge from Infest and start hitting. Atrophy Aura also reduces the target's damage, making it much harder for them to fight back against Lifestealer once he's on top of them. The two kits create a self-contained ganking package that is very difficult to survive without prior warning.

This global threat forces the enemy team to play much more carefully once Underlord has his ultimate. They can't safely split the map to farm, because Underlord and Lifestealer can punish any isolated hero. The counterplay relies on deep vision to spot the Fiend's Gate channel or having enough instant disables to lock Underlord down the moment he appears. The combo also works in reverse as a reliable escape; if Lifestealer gets caught out, he can Infest a nearby Underlord, who then teleports them both back to the safety of a tower or their base. This resilience makes them a constant problem to deal with.