How is the above stage glitch performed? the WR video is gone :(

can this game be completed co-op with only box wizard?

To complete a Heretic% run, one must acquire the Lifeblood Core without charms that give Lifeblood masks. In other words, one must enter the Abyss having harvested 15 masks worth of Lifeblood Cocoons, and acquire the Lifeblood Core.

Due to the nature of the challenge, this run would have to be completed nearly benchless, and therefore virtually charmless, relying instead on pathing, very careful combat, and platforming. Since there are eight total Lifeblood cocoons, each requiring certain skills to reach, and doling out a total of 19 masks, the routes and strategies for this category would absorb a lot of optimization before being perfected, if it ever is.