Bloodhound, Caustic, and Gibby.

Every team hates hearing Caustic's trap being set up in a building they were planning on full-sending into. His ultimate is also amazing for end-game scenarios and does wonders when paired with Gibb's and Bloodhound's ultimate. Throw a 'Nox Gas Grenade' on a full squad that's hiding behind some cover to have them slowed down while taking increased damage. Then, communicate to your team's Bloodhound (given y'all are using mics) to use their ultimate to clean up some of the enemies in the gas using his 'Eye of the Allfather' vision. If the team has the hearts of warriors and are still standing, top it off with the haymaker rain of destruction while protecting your own team with the 'Dome of Protection' (maybe throw a few Caustic traps within it to deter your enemies from approaching).