Spectre + Io

Why this works

Haunting onto an isolated support is one thing, but arriving with a tethered Io is another. Spectre's global initiation is backed up by all of Io's sustain and damage buffs. Tether and Overcharge make her extremely difficult to kill, even for multiple heroes, turning what should be a trade into a clean kill for Spectre. This allows her to join fights much earlier and more aggressively than she normally could. The safety net Io provides is immense, letting Spectre farm for her late-game items while still being a constant threat across the map.

This forces the enemy team to play defensively and stick together long before they're ready. Farming pushed-out lanes becomes a death sentence, as Spectre can appear at any moment with a full health battery. The counter-play involves drafting heavy, instant lockdown and burst to try and kill Spectre before Io's healing can catch up. Alternatively, teams might try to pressure Io himself, but a good Io player is notoriously hard to catch. The duo's global pressure with both Haunt and Relocate simply suffocates the map, accelerating Spectre's farm while starving the opposition.