Amaterasu

You can conjure inextinguishable black flames that emit no light. You can shape them, mold them, target with them, add damage to weapons, boost defense, or any other task that the DM allows. This is a Concentration spell. Your eyes must be open for this spell to work, but you can blink. If you are blinded in any way, the spell ends. State to the DM which use you will make of the spell. This spell does necrotic & fire damage. If a creature is immune to one of these or resistant to both, it takes half damage, & no damage if immune to both. It takes 3/4 damage if resistant to one of these.

Direct: You look at a creature to, instantly, ignite it. If there is no way for the creature magically extinguish it, or if there is no way for the creature to form a layer of something in between it & the fire (like a force field, a liquid, or a spell), then the creature must make a Con save or take 10d10+1 fire damage at the beginning of each of the turns it is on fire, & half damage on a successful save.

Darts: You can control the flames into the shape of 4 5ft darts. On impact, the dart causes the same effects as states before, but it adds 4d8 magical piercing damage. The speed of these darts are 100ft.

Defense: You can visually cast an 8th level spell slot of "Wall of Fire", but it doesn't extinguish until dispelled or triggered. It uses d10's+1 instead of d8's.

Armor: You can aid up to 3 allies' armor. This boosts their AC by +3, they are resistant to fire & necrotic damage. If they have a shield &/or armor, they both get +2 each.