The single-hit ability formula

Riot patch notes write many spell numbers as AP coefficients—for example, 300 AP. At the normal 100 AP baseline, that produces 300 raw damage before crit, amp, and defenses. This is the calculator's first input.

Enter the unit's final in-combat AP, not bonus AP. Baseline is 100. Rabadon's Deathcap adds 55 percentage points and also grants 15% Damage Amp; Jeweled Gauntlet adds 35 AP. Blue Buff grants 10% additional AP from all sources, so its final panel value is best read in combat.

Units have 25% base crit chance and 140% total crit damage, but ordinary ability damage cannot crit without Precision. With Precision, expected crit multiplier is 1 + crit chance × (crit damage - 1). Each additional Precision grants 10% crit damage. Crit chance above 100% converts to crit damage at 50% value.

Enter total Damage Amp as one percentage. This is separate from AP. Current Rabadon's Deathcap contributes 15% Damage Amp in addition to its +55% AP; both multipliers must be included.

For non-negative MR, the retained magic damage is 100 / (100 + MR). Void Staff applies 30% Shred to targets it damages for 5 seconds. Shred effects do not stack, so use the strongest active value rather than adding several together.

Durability reduces incoming damage. This input represents the target's total active value. Champion-specific scripts, item proc damage, executes, shields, healing, repeated casts, targeting, and snapshot timing are outside this single-hit model.