# Diablo IV mechanics and tech How the damage systems actually combine: multiplier stacking, snapshotting, breakpoints, uptime loops and the stats that look strong but are not. - [100% Block Chance quietly converts a conditional shield stat into an always-on Damage Reduction source](https://buildsmith.net/d4/tech/100-block-chance-quietly-converts-a-conditional-shield-stat-into-an-always-on/) - [100% Crit Chance is a hard ceiling with zero benefit beyond it - and going near it is usually itself a mistake](https://buildsmith.net/d4/tech/100-crit-chance-is-a-hard-ceiling-with-zero-benefit-beyond-it-and-going-near-it/) - ['All Damage Multiplier' affixes secretly count in every elemental Summed Multiplier bucket at once](https://buildsmith.net/d4/tech/all-damage-multiplier-affixes-secretly-count-in-every-elemental-summed/) - [Attack Speed and Cast Speed are two separate 100% pools, not one shared 200%](https://buildsmith.net/d4/tech/attack-speed-and-cast-speed-are-two-separate-100-pools-not-one-shared-200/) - [Attack Speed only matters in discrete jumps - the space between two frame breakpoints is a complete dead zone](https://buildsmith.net/d4/tech/attack-speed-only-matters-in-discrete-jumps-the-space-between-two-frame/) - [Barbarian's 100%-uptime Berserking loop: bypass Basic Skills entirely and cycle Core/Weapon-Mastery skills](https://buildsmith.net/d4/tech/barbarians-100-uptime-berserking-loop-bypass-basic-skills-entirely-and-cycle/) - [Barrier is a true damage-prevention buffer that always absorbs before Life, and multiple Barriers add together (with separately-tracked durations)](https://buildsmith.net/d4/tech/barrier-is-a-true-damage-prevention-buffer-that-always-absorbs-before-life-and/) - [Barrier size is almost certainly locked in at the moment it's granted, not recalculated as your Max Life changes afterward](https://buildsmith.net/d4/tech/barrier-size-is-almost-certainly-locked-in-at-the-moment-its-granted-not/) - [Choosing a Prime Evil Splinter is a semi-permanent, activity-shaping decision, not a simple stat pick](https://buildsmith.net/d4/tech/choosing-a-prime-evil-splinter-is-a-semi-permanent-activity-shaping-decision/) - [Cooldown Reduction sources shrink each other's value - one big CDR source always beats several small ones](https://buildsmith.net/d4/tech/cooldown-reduction-sources-shrink-each-others-value-one-big-cdr-source-always/) - [Critical Strike Damage and Vulnerable Damage each secretly split across two different buckets depending on wording](https://buildsmith.net/d4/tech/critical-strike-damage-and-vulnerable-damage-each-secretly-split-across-two/) - [Damage Reduction multiplies your effective HP, but Maximum Life sets the absolute floor for surviving one outlier hit](https://buildsmith.net/d4/tech/damage-reduction-multiplies-your-effective-hp-but-maximum-life-sets-the/) - [DoTs freeze certain buffs into themselves at the moment they're applied - this is the single biggest snapshotting mechanic in the game](https://buildsmith.net/d4/tech/dots-freeze-certain-buffs-into-themselves-at-the-moment-theyre-applied-this-is/) - [Fortify is the opposite of a snapshot - it is re-evaluated live on every single incoming hit](https://buildsmith.net/d4/tech/fortify-is-the-opposite-of-a-snapshot-it-is-re-evaluated-live-on-every-single/) - [Fortify slowly converts itself into Life every tick, creating a passive healing loop that also sustains Fortify-gated bonuses](https://buildsmith.net/d4/tech/fortify-slowly-converts-itself-into-life-every-tick-creating-a-passive-healing/) - [Fortify's real defensive value is protecting the 'bottom' of your Life bar from a single big hit, not a flat 10% damage cut](https://buildsmith.net/d4/tech/fortifys-real-defensive-value-is-protecting-the-bottom-of-your-life-bar-from-a/) - [Legacy Runewords crafted through the Horadric Cube sidestep the normal 2-socket item limit entirely](https://buildsmith.net/d4/tech/legacy-runewords-crafted-through-the-horadric-cube-sidestep-the-normal-2-socket/) - [Lucky Hit is a multiplicative double-roll, and chained procs are deliberately blocked - know both halves before building around it](https://buildsmith.net/d4/tech/lucky-hit-is-a-multiplicative-double-roll-and-chained-procs-are-deliberately/) - [Minions only double-dip on a FRACTION of your stats - gearing purely for 'self' damage under-delivers for a minion build](https://buildsmith.net/d4/tech/minions-only-double-dip-on-a-fraction-of-your-stats-gearing-purely-for-self/) - [More Season 15 launch instability: Splinter of the Mother's stacks not clearing, and Messerschmidt's Reaver healing enemies - both patched](https://buildsmith.net/d4/tech/more-season-15-launch-instability-splinter-of-the-mothers-stacks-not-clearing/) - [Not everything snapshots - 'while Vulnerable'-worded bonuses instead re-check live, every tick](https://buildsmith.net/d4/tech/not-everything-snapshots-while-vulnerable-worded-bonuses-instead-re-check-live/) - [Only five (really six) things are true damage multipliers - everything else is additive noise inside them](https://buildsmith.net/d4/tech/only-five-really-six-things-are-true-damage-multipliers-everything-else-is/) - ['+Overpower Damage%' and 'x% damage while Overpowering' are two completely different mechanics that look similar](https://buildsmith.net/d4/tech/overpower-damage-and-x-damage-while-overpowering-are-two-completely-different/) - [Overpower fundamentally changed mechanics in the Lord of Hatred era - old guides describing a crit-like proc chance are describing a dead mechanic](https://buildsmith.net/d4/tech/overpower-fundamentally-changed-mechanics-in-the-lord-of-hatred-era-old-guides/) - [Overpower stacks require active refresh maintenance - each stack silently expires on its own 4-second timer](https://buildsmith.net/d4/tech/overpower-stacks-require-active-refresh-maintenance-each-stack-silently-expires/) - [Overpower's baseline stack cap is disputed between sources (4 vs 8) - but is confirmed extendable far beyond either via specific items](https://buildsmith.net/d4/tech/overpowers-baseline-stack-cap-is-disputed-between-sources-4-vs-8-but-is/) - [Paladin's Block-into-Retribution loop removes the cooldown gate on its core damage skill entirely](https://buildsmith.net/d4/tech/paladins-block-into-retribution-loop-removes-the-cooldown-gate-on-its-core/) - [Paragon Glyphs jump in power at three specific levels - dumping XP evenly across many Glyphs wastes those breakpoints](https://buildsmith.net/d4/tech/paragon-glyphs-jump-in-power-at-three-specific-levels-dumping-xp-evenly-across/) - ['Pre-buff, then apply' is the core DoT-build execution loop this mechanic enables](https://buildsmith.net/d4/tech/pre-buff-then-apply-is-the-core-dot-build-execution-loop-this-mechanic-enables/) - [Prime Evil Iconic Powers are a genuinely 'free' uptime engine - they trigger automatically with no resource cost or input required](https://buildsmith.net/d4/tech/prime-evil-iconic-powers-are-a-genuinely-free-uptime-engine-they-trigger/) - [Prime Evil Iconic Powers scale off your CURRENT weapon damage and level, not a value frozen when you chose your Splinter](https://buildsmith.net/d4/tech/prime-evil-iconic-powers-scale-off-your-current-weapon-damage-and-level-not-a/) - [Refreshing a DoT early blends the old and new instances instead of simply replacing or stacking them](https://buildsmith.net/d4/tech/refreshing-a-dot-early-blends-the-old-and-new-instances-instead-of-simply/) - [Resource Cost Reduction stacks the same diminishing-returns way as Cooldown Reduction](https://buildsmith.net/d4/tech/resource-cost-reduction-stacks-the-same-diminishing-returns-way-as-cooldown/) - [Rogue's Preparation Specialization turns your Ultimate into a full cooldown-reset engine](https://buildsmith.net/d4/tech/rogues-preparation-specialization-turns-your-ultimate-into-a-full-cooldown/) - [Season 15 guidance explicitly warns minion-build players not to overcap stats - because how much minions inherit is itself disputed](https://buildsmith.net/d4/tech/season-15-guidance-explicitly-warns-minion-build-players-not-to-overcap-stats/) - [Season 15 launch bug: Rogue's Dance of Knives scaled damage infinitely, clearing Pit 150 within hours - patched in Hotfix 2](https://buildsmith.net/d4/tech/season-15-launch-bug-rogues-dance-of-knives-scaled-damage-infinitely-clearing/) - [Season 15 launch bug: transmuting three Ancestral Stealth Runewords incorrectly granted Enigma's teleport power - patched](https://buildsmith.net/d4/tech/season-15-launch-bug-transmuting-three-ancestral-stealth-runewords-incorrectly/) - [Soul Splinters are a deliberate high-risk/high-reward socketable system - the drawback is the balancing act, not a rounding error](https://buildsmith.net/d4/tech/soul-splinters-are-a-deliberate-high-risk-high-reward-socketable-system-the/) - [The Additive bucket punishes you exponentially harder the more you've already put in it](https://buildsmith.net/d4/tech/the-additive-bucket-punishes-you-exponentially-harder-the-more-youve-already/) - [The best Vulnerable-uptime builds apply it as an automatic side-effect of their main damage skill, not as a separate action](https://buildsmith.net/d4/tech/the-best-vulnerable-uptime-builds-apply-it-as-an-automatic-side-effect-of-their/) - [The exact formula for comparing a new Additive roll against a new Global Multiplier](https://buildsmith.net/d4/tech/the-exact-formula-for-comparing-a-new-additive-roll-against-a-new-global/) - [The Horadric Cube's one-Crafted-Mythic-equipped limit is back, but ONLY for the Cube's Upgrade Direct recipe](https://buildsmith.net/d4/tech/the-horadric-cubes-one-crafted-mythic-equipped-limit-is-back-but-only-for-the/) - [TRAP: buying more Attack Speed inside your skill's dead zone feels productive but does nothing](https://buildsmith.net/d4/tech/trap-buying-more-attack-speed-inside-your-skills-dead-zone-feels-productive-but/) - [TRAP: chasing lots of small conditional Damage Reduction affixes instead of one large unconditional source](https://buildsmith.net/d4/tech/trap-chasing-lots-of-small-conditional-damage-reduction-affixes-instead-of-one/) - [TRAP: Critical Strike Chance beyond 100% is pure waste - but it's an easy trap because gear naturally overshoots it](https://buildsmith.net/d4/tech/trap-critical-strike-chance-beyond-100-is-pure-waste-but-its-an-easy-trap/) - [TRAP: gearing a minion build's Crit Chance/Attack Speed as if minions were you](https://buildsmith.net/d4/tech/trap-gearing-a-minion-builds-crit-chance-attack-speed-as-if-minions-were-you/) - [TRAP: more +Vulnerable Damage% gear rolls once your Additive bucket is already huge](https://buildsmith.net/d4/tech/trap-more-vulnerable-damage-gear-rolls-once-your-additive-bucket-is-already-huge/) - [TRAP: Movement Speed above the 200% cap is invisible dead weight](https://buildsmith.net/d4/tech/trap-movement-speed-above-the-200-cap-is-invisible-dead-weight/) - [TRAP: swapping to a Horadric Seal for its stat bonus while losing a Charm slot](https://buildsmith.net/d4/tech/trap-swapping-to-a-horadric-seal-for-its-stat-bonus-while-losing-a-charm-slot/) - [Two 25% Damage Reduction sources are worse than one 50% source - DR stacking math punishes fragmentation](https://buildsmith.net/d4/tech/two-25-damage-reduction-sources-are-worse-than-one-50-source-dr-stacking-math/) - [Warlock's Ritualist Shard + Overwhelming Aspect turns Overpower into the build's primary damage multiplier via forced overstacking](https://buildsmith.net/d4/tech/warlocks-ritualist-shard-overwhelming-aspect-turns-overpower-into-the-builds/) - [Weaken is a flat, non-scaling debuff whose value depends entirely on WHAT you hit, not how much Weaken you stack](https://buildsmith.net/d4/tech/weaken-is-a-flat-non-scaling-debuff-whose-value-depends-entirely-on-what-you/) - [Weaken is a genuine, stacking-with-everything-else active mitigation tool against exactly the enemies most likely to one-shot you](https://buildsmith.net/d4/tech/weaken-is-a-genuine-stacking-with-everything-else-active-mitigation-tool/) - ['x% Critical Strike Damage Multiplier' and plain 'x% Critical Strike Damage' are NOT the same bucket - misreading this dilutes your best items](https://buildsmith.net/d4/tech/x-critical-strike-damage-multiplier-and-plain-x-critical-strike-damage-are-not/) - [Your character sheet's Toughness number describes average sustained mitigation, not one-shot survivability](https://buildsmith.net/d4/tech/your-character-sheets-toughness-number-describes-average-sustained-mitigation/) - [Your Horadric Seal choice is a charm-SLOT-COUNT decision first, and a stat-bonus decision second](https://buildsmith.net/d4/tech/your-horadric-seal-choice-is-a-charm-slot-count-decision-first-and-a-stat-bonus/)