The only issues I have are with the Battlenet launcher, it sometimes crashes during startup when first opening D4 seemingly at random but once the game is running I don’t have any issues. Currently running it on Proton Experimental.

As far as settings go, at default settings D4 seems to be extremely taxing on the GPU (constant >=97% usage, high temps, crashes regularly after running for a while), although this seems to be common to all systems including PS5/Xbox.

Locking refresh rate and in-game menu FPS to 50fps keeps the power and GPU usage much lower and I get stable performance with no crashes.

Following up again. It’s much better playing with a 45 FPS cap and with FSR off than 60 cap and FSR on.

Setup and you're good to go. The game actually runs fantastically well on the Deck. Medium settings with FSR 2 Balanced drains 15W in dungeons and the open world, 23W in town. Hits a flat 40fps so if you frame limit in-game and set the Steam Deck to run in 40Hz mode, you get ultra smooth gameplay.