This mod is a combat-and-progression mod built around fighting echoes of the past: hooded spellblade "Simulacra" that culminate in a three-phase boss, The Realmwalker.
This mod has an extra weapon layer that unlocks if you also have Spell Engine and related RPG Series mods installed.
Simulacra can spawn several ways:
Stone-circle shrines generate in the Overworld and spawn a Simulacrum on the spot.
Events occasionally spawn a wandering Simulacrum near you (about as rare as a wandering trader); these despawn if left alone.
Resonant Artifacts: found by brushing suspicious sand/gravel and in buried treasure, desert pyramids, ancient cities, and abandoned mineshafts. Right-click to shatter one and summon a Simulacrum to fight on demand.