Clockwork Spider Turret.
I love playing the demon hunter, but some skills that constantly needs refreshing have me skipping entire builds (Marauder) because I keep forgetting the sentries.
My suggestion is to change ‘Chain of Torment’ into a permanent minion, and switch position with the ‘Guardian Turret’ rune, Pushing Guardian Turret down one spot and have my suggestion at the highest level spot.
A unique item that makes turrets into pets could also work:)