Crusaders lock Dominic Bird was sent to the sin bin for 10 minutes after a blatant shoulder charge sent Chiefs No 8 Liam Squire out of the game. Bay of Plenty's All Blacks flanker Sam Cane replaced him.
Crusaders captain Kieran Reid and Chiefs halfback Tawera Kerr Barlow were also out of the game after heavy knocks to the head.
Anscombe kicked his fourth penalty to put the Chiefs in front 12-9 before some great work from Cane set up a turnover, which former Crusader Tom Marshall cleverly finished off with a try in the corner as the siren sounded.
Halftime: Chiefs 17 Crusaders 9.
The Chiefs started the second spell with 26 phases in possession attacking the Crusaders line but the defence held.
Slade closed the gap to 17-12 with a penalty and then hit the post with a sitter from in front.
The unyielding battle between the evenly matched foes continued without further scoring until the 68th minute when Slade finally kicked another penalty after hitting the post again with another shot.
Bay of Plenty front rowers Nathan Harris and Josh Hohneck joined the fray for the Chiefs.
Slade kicked his 6th penalty to regain the lead for the Crusaders with 10 minutes to play.
Crucially, the Chiefs had an attacking lineout feed ruled out with just two minutes play after a video review of a late tackle on Andy Ellis, and then in the final play of the match won a penalty on halfway.
Up stepped Anscombe with a difficult kick in misty conditions from 52 metres but the ball flew just left of the posts to give the Crusaders the win.
Crusaders 18 (Colin Slade 6 pens) Chiefs 17 (Tom Marshall try; Gareth Anscombe 4 pens). Halftime: Chiefs 17-9
