Effect: +0.1% Damage per kill, up to +100% (1,000 kills per copy). Permanent within a run.
Unlock: Reach Level 30 as Calcium
Demonic Soul is an Epic item that permanently increases your Damage stat by +0.1% for every enemy you kill during the run. The bonus accumulates until it reaches its cap of +100% at 1,000 kills - at which point you have effectively doubled your damage output from this item alone. Unlike many items, the stacks are permanent within a run and do not reset between waves or stages.
The wiki describes it as "one of the strongest scaling items in the game" precisely because of this permanence. Every kill you made in the first 5 minutes of the run still contributes to your damage in the final swarm. Builds that generate high kill counts early - through Cursed Tome enemy density, AoE weapons, or chain mechanics - can reach the cap well before the later stages where the bonus matters most.
Picking up additional copies of Demonic Soul does not reset your existing stacks. Instead, each copy raises the cap by 1,000 stacks and adds +1 stack per kill. Your existing progress carries over to the new higher ceiling. Per community testing at megabonkinfo.org:
| Copies | Stacks per Kill | Cap | Max Bonus | Kills to Cap from 0 |
|---|---|---|---|---|
| 1 | 1 | 1,000 | +100% | 1,000 |
| 2 | 2 | 2,000 | +200% | 1,000 total |
| 3 | 3 | 3,000 | +300% | ~1,334 total |
| 4 | 4 | 4,000 | +400% | ~1,250 total from 3k |
The practical benefit of stacking is not just a higher damage ceiling - it is also a faster path to that ceiling. Two copies means you accumulate stacks twice as fast, so you reach +200% damage in roughly the same number of kills it would take one copy to reach +100%. Late-game picks of additional copies extend an already-substantial bonus without losing any prior progress.
If you find a second Demonic Soul after already capping the first at 1,000 stacks, that second copy immediately extends the cap to 2,000 and starts gaining 2 stacks per kill from that point. You do not lose the +100% you already earned. A second copy found at stage 2 in a long run can push you from +100% to +200% damage for the remainder of the run without any wasted kill progress.
Reach Level 30 as Calcium in a single run. Calcium's Speed Demon passive makes high XP accumulation straightforward - his constant movement keeps him in contact with enemy packs, and his Bone starter weapon's bouncing projectiles generate consistent kills for leveling. Prioritize XP Tome and Cursed Tome to accelerate level gain. Forest Tier 1 is sufficient - you do not need a high-tier run.
Amog - Amog's Plague passive causes poisoned enemies to explode on death and spread poison to nearby enemies. Each Plague explosion can chain-kill multiple enemies simultaneously, generating Demonic Soul stacks far faster than single-target kills would. An Amog run with full poison coverage can reach the 1,000-kill cap in a fraction of the time a non-chain build would take. Demonic Soul's damage bonus also amplifies the poison and explosion damage directly, creating a positive feedback loop where more damage kills enemies faster which builds more stacks.
Megachad - The wiki directly names Aura and Firestaff as the synergy weapons for Demonic Soul. Megachad starts with Aura as his default weapon, making him the character most naturally aligned with the wiki's recommendation. Aura deals constant 360-degree tick damage to every enemy in range simultaneously, generating kills at a steady rate throughout the run without any active targeting. His AFK playstyle also means he remains in swarms consistently rather than kiting away, keeping the kill rate high and Demonic Soul stacks accumulating continuously.
Robinette - Robinette's Stonks passive increases damage based on gold held. Robinette runs typically include Cursed Tome for enemy density, which spawns significantly more enemies per wave. More enemies means faster Demonic Soul stacking, and the increased kill count also means more gold from drops which feeds Robinette's own damage scaling. The two per-kill damage sources - Demonic Soul's flat +0.1% and Robinette's gold-driven scaling - both benefit from the same high enemy density created by Cursed Tome, making them naturally complementary in the same build.
+0.1% Damage permanently per kill, capping at +100% after 1,000 kills per copy. The bonus is permanent within a run. Multiple copies raise the cap by 1,000 and add +1 stack per kill each, and existing stacks carry over when new copies are picked up.
Reach Level 30 as Calcium in a single run. Prioritize XP Tome and Cursed Tome for fast leveling. Forest Tier 1 is sufficient. After meeting the condition, purchase Demonic Soul from Main Menu - Unlocks - Items with Silver.
Yes. Each additional copy adds +1 stack per kill and raises the cap by 1,000 stacks. Existing stacks carry over - picking up a second copy after reaching the 1,000-kill cap with the first immediately extends the ceiling to 2,000 without losing your progress. Two copies at full cap gives +200% Damage, three gives +300%, and so on.
Demonic Soul gives +0.1% Damage per kill (up to +100% from 1,000 kills). Demonic Blood gives +0.5 Max HP per kill (up to +100 Max HP from 200 kills). Both are per-kill scaling items that reward the same high-kill playstyle. Demonic Blood caps faster but provides survivability, while Demonic Soul takes longer to cap but provides a larger and more impactful damage bonus.
