Overview
This is a Cast-on-Crit Arc build for the Gemling Legionnaire, shown off as a 200% Delirium farmer that lights up the entire screen in chained lightning. The premise is a double Cast-on-Crit setup: your attacks crit, the trigger fires Arc, and the Gemling’s alternate gem-quality bonus pushes Arc to chain up to roughly fifty times, so a single proc cascades across a whole pack. The creator pitches it as a build that clears full screens, sustains its own mana, and stacks high item rarity (around 85%) for currency farming while staying tanky enough to push deep Delirium.
This writeup is based on the creator’s published showcase and overview — the video is an early-access sneak peek of a build that is still in active development, with a full guide and a public Path of Building to follow. Treat the numbers as the creator’s own claims rather than finalised values, and check back against the full release for the confirmed tree, gear and gem links.
Pros & Cons
Pros
- Full-screen clear from Arc chaining roughly fifty times via the Gemling gem-quality bonus
- Double Cast-on-Crit with built-in mana sustain, so it keeps firing without manual casting
- High item rarity (~85% claimed) makes it a strong currency and Delirium farmer
- Creator reports it staying tanky enough to run 200% Delirium
Cons
- Early-access showcase: the full build, tree and public PoB are not released yet
- Cast-on-Crit trigger chains are gear-hungry and assume reliable critical strikes
- Defensive layering is described only in broad terms (“balanced DPS and tankiness”) in the showcase
- Not pitched as a league starter — it is an endgame farming setup
Key Skills
- Arc — the chaining lightning payload, boosted by the Gemling’s alternate gem quality to chain ~50 times
- Cast on Critical Strike (x2) — the double trigger core that fires Arc off your crits
- Mana sustain support / setup — the creator highlights consistent mana as a pillar of the build
Gear & Anointments
The showcase frames this as a crit-focused Cast-on-Crit caster on the Gemling Legionnaire, leaning on the ascendancy’s gem-quality scaling to maximise Arc chains, with an emphasis on item rarity for farming. Specific uniques, weapon bases, runes and the passive tree are not yet public — the creator notes the PoB is currently early-access only and a full build guide is planned. Specific gear should be confirmed against the full guide and PoB when released.
Endgame Notes
Positioned squarely as an endgame Delirium and mapping farmer: the draw is full-screen clears at 200% Delirium combined with high rarity for currency return. Single-target and pinnacle performance are not the focus of this showcase.
Credits & Source
Build credited to FastAFgaming. See the source video for the gameplay showcase, and the creator’s channel for the full build and Path of Building when released: The Strongest Double CoC Arc in 0.5 — 200% Deli Showcase.