Kusuma cast invisibility frequently which is certainly annoying, more important she walks over fire (so you can remove invisibility) but walks around energy, so u can totally avoid her auto attacks, that said is a pretty easy boss, u could create a T of walls to force her walk over fire constantly avoiding her invisibility or even could create a corner with energy and 2 fire field rune so she will be constantly walking on diagonal.
Beside her invisibility doesn't have any mechanics, she does a lot of death/earth damage tho.
since she can be walkable around energy it turns her really easy, can be killed since lvl 150 with pretty good set even probably a bit earlier yet lvl 250 at least is recommended
is important to bring earth and death protection (either SSA or Sacred tree amulet) and keep using something to remover her invisibility (fire walls, constantly using aoe runes/spells, paladin could use exana ina, etc) and if low lvl player you could follow this strategy to avoid damage:
Walls: as shown in the image below, you can use fire wall to force kusuma walk over it and remove her invisibility, from the red dot sqm throw a wall either at diagonal (1sqm below chest) or just frontal (1sqm north from red dot sqm) the diagonal sqm wall would be shown as in the image but with 1 extra sqm diagonal north from your position, this extra sqm must be removed if we want to create a corner, so we would move to the blue dot sqm and throw a wall 1 sqm at east, so that way the wall will have only 3 sqm at north from our position and wouldn't close the entrance,
the frontal wall instead (creating a T with walls instead of a corner) must be placed first the energy wall then after the fire wall, so that it will keep being fire and wont force extra walk (and a corner) for kusuma.