I finished my second playthrough of the Elden Ring DLC and the entire playthrough overall. I tried and tried to beat the final DLC boss without using summons or ashes, but the closest I got over many attempts was about ~30% health. I eventually broke and used mimic tear for the 2nd phase and beat it the 2nd time I reached that point. I've also been playing some XCOM2 on commander difficulty
I've been getting some use out of ambush to whittle down enemy forces in prolonged sieges against some of the huge armies that'll sometimes form. If you can smack down a notable during the raid, all the better.