Wagyu: The fat will render when the meat warms up, and long before it get hot enough to cook.
I sear the wagyu I cook, and that's about it.
Steaks I do at 700f, but low and slow wagyu is of no interest for me so I cannot advise.
The only current member banned for life!
I could help being the way I am, but the problem is...there is nobody else willing to do it.