Issun’s Accomplice challenges player movement and positioning with a barrage of area of effect spells that cover large portions of the arena in fire. Inherent with the Oni’s arsenal is Mark of the House, a spell that consists of a circle of flame that radiates outward in the shape of an X through the openings of four additional, yet larger, flame circles seven meters apart placed to the left, right, front, and back sides of the player, all of which ignite the ground in fire for a short time. The central focus of the spell originates at the location where the player is standing once the spell is finished being cast, giving players a period of two seconds to consider the best place to stand for the carnage to unfold.
An ideal position for you to be in preparation for this spell must take into account the possibility that the boss is equipped with the Pitched Fork module. With Pitched Fork, the area around the Oni erupts in flames, spreads outward in the shape of a devil’s pitchfork–the handle shooting out from the Oni’s back and the fork from its front–scorching the ground for a short time, dealing significant damage, and applying a Burning stack for every second a player stands in it. The direction in which the fire spreads leaves the area to the Oni’s sides safe to go for relief from the flames. Because the slim gaps in the shape of a V within Mark of the House are also safe from the fire, standing face-to-face with the boss and stepping back 5 - 7 meters before Mark of the House has finished being cast will leave a small circle open to stand in front of you within melee range of the boss and give you a narrow escape route to your left or right if the boss responds with another area of effect spell.
Allow me to demonstrate. I encountered Issun’s Accomplice on the first branch of Dark Agartha with Memory of Flame, Weakening, and Pitched Fork as active modules:
Notice how, while dodging along the path out of Pitched Fork from within the hazard zone left in the wake of Mark of the House I’m given the option to re-engage immediately or rush out farther towards the edge of the platform using the extra speed from the Signet of Quickness to compel the boss back into attack range away from imminent danger.
The same tactics used for Mark of the House with Pitched Fork in mind apply to the Flamesurge, Immolation, and Meteor Shower modules. The first two spells are both large, circular area of effects targeted at your current location that cause a Burning affliction, but Flamesurge deals a large amount of damage in a single hit, while Immolation persists on the ground, dealing damage every second, and applying a Burning effect that grows in strength every second you stand in the fire. Meteor Shower, however, is a channeled spell that rains down meteors on the ground over an extended period of time that deal damage to you, knock you down, and leave in their wake burning pools of fire, demanding from you a reactive, rather than a proactive, response, since there’s no way to predict whether a meteor will home in on your position. Whatever the circumstance requires, there need not be excessive combat downtime when you have foresight and deft control of where the Oni’s spells are cast.
The unique threat the Oni poses, therefore, is to make you fight for every inch of neutral territory. Thoughtlessness in your movement or blindness to what is happening around you will cost you time navigating around or away from spells more than such carelessness will cost you your life. A battle that would have taken you a minute and a half can stretch out needlessly to three minutes. But know that there is room to make a mistake or step in the fire–if only for a moment–and still come out the victor. You’re not punished for imperfection any more than you are rewarded for complacency.