Venter announced that he would be leaving Edinburgh to join the Lions at the end of the current United Rugby Championship campaign.
Van Rooyen is not expecting the the Springbok prop to do them any favours when they take on Edinburgh, with him identifying the scrum as the set piece that is likely to define the encounter.
"We definitely feel we need to be more consistent in the scrums," he said.
"Boan has done really well over the past year, for Edinburgh and the Boks. I think he will want to prove a point on Saturday before he joins us next season."
The Lions are looking to extend their winning streak in the URC to three games after beating the Sharks and Stormers in consecutive weeks before a break in fixtures for the Six Nations.
Despite their success against local rivals, one area they struggled in both matches was at scrum time, and the powerful Edinburgh pack will definitely be looking to put them under pressure in that area.
"We are really proud of winning the SA Shield. But our work's not done yet," Van Rooyen said.
"In the last few seasons, we were dependent on other results going our way to qualify."
Edinburgh come into the match looking for a vastly improved performance after going down 40-19 against Ulster at home last time out.
They have also only won one of their four URC games so far in 2026 and need a strong run to close out the league phase if they are to stand any chance of making the playoffs.