Nioh - Sarutobi Sasuke - Way of the Nioh (No Items, No Ninjutsu or Onmyo, No Living Weapon)

The healing comes from receiving an elemental debuff, (ticking healing) or landing a perfect guard (700~ heal.)
Between 60-70 attempts. Super sick boss, a lot of his attacks are anime af and are super satisfying to dodge. A lot like Sanada Yukimura for this challenge, Sasuke does extreme stamina damage and damage in general, with 2 different dash-grab attacks that almost always lead to guaranteed death. The hardest part is that you're normally only able to land one attack before he'll dodge away or start guarding; getting a perfect guard and hitting him with Tempest was my go-to strategy for dealing high damage.
When he buffs his tonfa with fire, the explosive kunai are also extremely dangerous, guarding them should only be a last resort considering they stick anyway and you also need to guard the blast while Sasuke attempts to beat your stamina down to nothing, or grab you while you guard. Also beware of the bait where he just stands there hopping around, taking a swing at him triggers a counter-attack which is usually an insta-kill.