You must have 3 weapons/abilities, and a class ability.
You don’t have to make them match the same slot, but you can if you want.
There will be 3 other hunters fighting with you. If you took the trapper dome for your class ability, you’ll replace the trapper.
I would take Lazarus’ sniper rifle, Bucket’s sentries, Lazarus’s Invisibility, and the Assault’s shield. It would be the most aggressive trapper ever with zero ability to actually track the monster.