The Stormjaw Staff is a Pre-Hardmode summon weapon that drops from Stormlions. When used, it summons a miniature Stormlion minion. It runs on the ground and aggressively rams enemies back and forth, does not deal contact damage but creates damaging sparks in contact with enemies. Sparks linger for 2 seconds and partially ignore immunity frames, in a similar manner to the Amidias' Spark.
Its best modifier is Mythical. While Ruthless may seem to provide a bigger damage by percentages, rounding reveals that Mythical and Ruthless boost the damage equally for this weapon.