This guide will let you know where to get the Bullet Dance in Warframe.
Bullet dance can drop from two plagues in the void, which are the two void sabotage missions in you, and it doesn’t matter which one you run.
To get a chance at getting bullet dance, you will need to get C rotation rewards from the sabotage missions you do by getting all three orokin caches. You have to search about every room and listen out for the caches.
The mod has a low-mid drop rate, so it will probably take you a few runs before you possibly get the mod.