There is a lot to the customization of the Doom Slayer himself without making things unnecessarily complex. One way to gain perks and advantages against the demons of hell, are Runes and in this ...

Engrave your helm with the Pandemic rune: Periodic damage from your Corruption, Unstable Affliction, Curse of Agony, Immolate, Curse of Doom, and Siphon Life abilities can now be critical strikes.