Onmyo Magic
Onmyo Magic includes elemental attacks, weapon effects, and defensive or resistance spells. Its Jutsu are prepared at Shrines and limited by capacity.
How it works
The Nioh 2 wiki describes talismans for elemental attacks and spells that can boost defenses or resist specific elements. It also says Onmyo Magic can imbue weapons with elemental effects for a limited duration. Jutsu can be readied at a Shrine, assigned to quick slots, and constrained by preparation limits and overall capacity.
When it helps
Consider Onmyo Magic when elemental attacks, a temporary weapon element, defense, or resistance suits your needs. The source does not specify which element to choose for a given enemy here.
The tradeoff
Prepared Jutsu and total capacity are limited, and the described weapon elemental effect lasts for a limited duration.
Your next step
At a Shrine, review Onmyo Jutsu, check their capacity costs, and assign selected talismans to a quick slot.
Read the supporting references
Check the edition and source version for patch-specific details. Guide methodology.