the cactus item (from either this mod or retribution) is the one that spawns in every room in a random spot
the problem is one of the rooms this mod adds but I forgot its name is a single tile wide path around the room with invincible ghost going around, and you have to push the button on the other side. since the area space is only 1 tile wide, you can't dodge the ghosts, you have to run along with them. but with cactus, it will block a path and a ghost will hit it and change direction, meaning that you will now get sandwiched between ghosts moving in 2 opposite direction without any way to not get hurt before you can press the button.

I drew a quick sketch to illustrate what I'm trying to say and to show how it is impossible to not be hurt
https://media.discordapp.net/attachments/640372487468613639/789742677566291998/isaac.png?width=1502&height=1094