Eternal Calculus
Eternal Calculus is a 5★ Light Cone for the Path of Erudition in Honkai: Star Rail.
A 5-star Mage cone that grants solid base ATK plus stacking ATK per enemy hit (up to 5 stacks) and a SPD boost against 3+ targets, making it near-optimal for sustained DoT/AoE damage teams, earning SS tier.
Increases the wearer's ATK by 8%. After using an attack, for each enemy target hit, additionally increases ATK by 4%. This effect can stack up to 5 times and last until the next attack. If there are 3 or more enemy targets hit, this unit's SPD increases by 8%, lasting for 1 turn(s).
Eternally suspended in the void, Streams of shimmering data flood into THEIR mind. Turning all things past and future into symbols, THEY deduce the end from the beginning. Knowledge, answers, truths... In the mist of information, a brilliant light arises, And everything becomes clear to THEM.
How to read this Light Cone page
Every Light Cone has exactly one passive effect tied to the wielder's combat performance; that effect scales up as you Superimpose it from S1 to S5 — use the S1-S5 buttons above to see the exact numbers at each level instead of guessing or interpolating. A Light Cone only delivers its full value on a character who shares its Path; "Characters who use this cone" lists every character on that Path, while "Best users" is a narrower list pulled from real build consensus, not a guess.
Base stats (HP/ATK/DEF) are shown at Lv80 for every cone of the same rarity so they can be compared directly; a 5-star cone will always edge out 4-star and 3-star ones here — the real difference lives in the passive effect, not the flat stats. The "Alternative cones on the same Path" section suggests a few other options if you do not own the signature cone yet, or want to compare before spending ascension materials.
See the full list on the Light Cones page, or check terms in the HSR Glossary.