Alex Roach scored twice and set up another in regulation for the Hitmen (4-0-2), while Humphries, Brooks Macek and Brady Brassart all finished with a goal and an assist each. Cody Sylvester also scored, while Jaynen Rissling had two assists.
T.J. Foster scored four times for the Oil Kings (4-2-1), who also lost to the Hitmen 4-1 in Edmonton on Sept. 28. Michael St. Croix had a goal and an assist, while Dylan Wruck set up a pair of goals.
St. Croix scored a power-play goal for the Oil Kings at 19:19 of the third period to force overtime before Humphries scored the game-winning goal with Edmonton captain Griffin Reinhart serving a tripping penalty during the extra session.
Chris Driedger finished the game with 26 saves in the Hitmen net and improved his record to 4-0-1. Meanwhile, Edmonton netminder Laurent Brossoit stopped 26-of-32 shots he faced.
The Hitmen went 1-for-7 with the man advantage, while the Oil Kings converted 2-of-3 power-play opportunities.