Proper activation is important in every exercise, especially in a deadlift when you are using heavy weights. One of the trickiest things to master is a top position. Great activation in this position is crucial for spine safety and protecting your lower back when performing.
One particular exercise that can help you in mastering this position is deadlift variation with an elastic band. The band will help you achieve tension in top position by pulling you down. It will be easier for you to squeeze your glutes, lats and core muscles. The trick is that the band gives you active resistance and it is easier for you to learn how to create muscle tension.
I used a lot of variations with bands, but this particular I saw at Tony Gentilcore Instagram feed and it is great. If you are not familiar with his work, I truly suggest you visit his website and Instagram.