Crystal Vile Shard

One use plants a spike of crystal that grows outward from where you are standing, straight through walls, and it keeps hurting everything along its length instead of stopping at the first body. There is no travel time to account for and no line of sight to manage, which is what makes it the answer to enemies hiding behind terrain.

Range is short, though, and the tip carries the heavier hit. You end up standing much closer than you would with almost any other magic weapon of its era, which is comfortable against something slow and fatal against something that charges.

Segmented enemies. Since the spike pierces without limit, every worm segment sitting inside it takes a hit on every cast, so The Destroyer and the wyverns above the sky islands come apart absurdly fast, especially when a worm coils back over itself. The repeated knockback also pins smaller enemies in place long enough to finish them.

The one real weakness is that a modest base hit gets chewed up by enemy defense. The built in armor penetration helps and Ichor helps more, so pair it with something that applies that debuff before committing to it as a main weapon.