Honestly, I think some of it was dumb luck on how I situated the Duncan, and how I did some rockscaping.
I have AquaIllumination Blue SOL lighting and give it a fair bit of moderate to high light daily. I target feed all the corals with Oyster feast 1-2 x week depending on how they look.
The Duncan is doing awesome, as is my small Tubinaria, and Lobophyllia. However, I almost killed a very healthy Xenia due to poor placement and not reacting to how it was doing fast enough.
I hope everyone's Duncan's grow and prosper.
All the best