Farm Shards of Agony fast in Diablo 4 by looping Grigoire for reliable chest drops, topping up Living Steel in Helltides, and mixing in Varshan runs so your Duriel keys never dry up.
If you're chasing Mythic Uniques in Diablo 4, you'll notice pretty fast that Shards of Agony are the bottleneck. You can have the damage, the route, the patience, and still end up staring at an empty stash tab because Duriel isn't getting summoned for free. Some players shortcut the slow parts by trading for missing materials or gearing tweaks, and sites like U4GM (https://www.u4gm.com/) get mentioned a lot for that reason, but even if you're doing everything in-game, the real win is building a loop you can repeat without burning out.
Grigoire Loop and Living Steel
Grigoire, the Galvanic Saint, is still the workhorse farm. He's in the Hall of the Penitent in Dry Steppes, and you'll spend Living Steel to pull him in. So your schedule basically becomes: live in Helltides, cash out smart, then chain boss runs. Don't waste time on the cheap chests if you're serious—aim for Tortured Gifts that cost 300 Cinders, since they're the steady Living Steel source. If you spawn near Gea Kul, use the Voice of the Hell trick to speed up resets and keep your Cinders flowing. In a good group with strong builds, you'll chew through summons quickly, but even solo you'll feel the pace if you keep your Lightning Resistance capped, because his floor traps punish sloppy positioning.
Varshan as Your Side Hustle
People skip Varshan and then wonder why their shard count crawls. The Echo of Varshan in the Malignant Burrow isn't the headline, but it fits neatly into what you're already doing. You're running Whispers during Helltides anyway, grabbing Tree of Whispers caches, and dealing with Grotesque Debtors when they show up. Those are your Malignant Heart sources, and once you've got enough to summon, it's a quick detour for more Duriel fuel. The fight feels a lot nicer if you stack Shadow Resistance and don't get cute with greedy melee windows.
Undercity Runs if You Have Vessel of Hatred
If you've got Vessel of Hatred, the Kurast Undercity is a welcome change of scenery, and it's not just "for fun." Using a Tribute of Titans can spike the material drops, including the stuff you care about for Duriel. The rhythm is simple: farm tributes from higher-tier Nightmare Dungeons (Tier 50+ tends to feel efficient), then run Undercity in tight bursts. Ten minutes here, back out, reset, go again. It breaks up the Helltide grind and keeps your attention from drifting.
Rotations, Not Hero Mode
The fastest way to hit a big shard stack is refusing to farm alone. Four-player rotations stretch everyone's materials, and the pace stays high because someone's always ready to pop the next summon. Set clear rules at the start, stick to the order, and you'll avoid drama. Once you've got enough, head to the Gaping Crevasse in Kehjistan and run Duriel until your eyes blur, and if you're short on gold for repairs, rerolls, or just keeping the loop moving, folding in a reliable source like Diablo 4 Gold can make the whole session feel smoother without turning it into a second job.