You wouldn't normally expect a boss in Elden Ring to die slowly and in a terrifying manner, but toxic builds can be an excellent and even efficient way to defeat tough bosses.
Poison is OVERPOWERED – Destroy everything with infinite buffs – Best Elden Ring Status Build Guide!
This guide will also cover Rot, the stronger version of Poison in Elden Ring. While Rot has significantly less synergies compared to Poison, you can still use it to deal more damage to a boss.
When a weapon scales with Arcane, it increases the scale of the weapon's innate Poison. We want a healthy amount of Arcane, but also enough Dexterity or Strength to deal good physical damage. For this purpose, we'll start as a Bandit, though most starting classes can reach this point without issue. This build is also designed around level 120, though higher levels just pump out similar stats.
Poison scales from Arcane, as long as the weapon or Seal you're using to apply the poison has Arcane scales. 60 is Arcane's soft cap, so it's a pretty good point to stop at. 40 Vigor is similar, with each point of Vigor giving diminishing returns compared to previous levels, so it's a good idea to get there.
