Conjure Bone Spears

You create a Bone spears rising from the ground. Each creature in the area of the spell  must succeed on a Dexterity saving throw. A creature takes 2d8  damage on a failed save, or half as much damage on a successful one. The damage type is piercing.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d8 for each slot level above 1st.

But the cost of component increases every 2 level increase. Level 1( 1 corpse ) Level 2( 1 corpse ) Level 3 (2 corpses) etc.