**Quick summary**

1. Bosses have 2.1 magic crit reduction.

2. Dark Conviction is active only if you have weapon equipped. Ebon Plaguebringer is always active.

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While a melee crit depression rate of 4.8 against bosses is well known, I did not find such a number for magic.

The biggest topic on this subject I could find had speculations on the figure being from 0 to 3, but again no hard data.

Vontre's DK sheet for example shows basic magic crit chance as +0.91.

All of the tests performed on the boss dummy in Darnassus given how it's a place no one ever visits and won't corrupt the data with possible debuffs.

Test 1 (data removed, appears to be corrupt)

Test 2

Gear: 108 hit rating (4.12), 199 crit rating (4.33)

Talents: 4 in dark conviction, 3 in rime

IT = 3851 casts, 511 miss (13.27), 567 crit (14.72)

DC+BB = 6800 casts, 871 miss (12.8), 122 crit (1.79)

(19.33-X)*0.8712=14.72; X=2.43 [6.43 if DC works]

(4.33-X)*0.8712=1.79; X=2.27 [6.27 if DC works]

Test 3

Gear: 108 hit rating (4.12), 199 crit rating (4.33)

Talents: 2 in dark conviction, 3 in ebon plaguebringer, 3 in virulence

DC: 4370 casts 423 miss 195 crit

IT: 5733 casts 560 miss 259 crit

BB: 5708 casts 543 miss 296 crit

All: 15811 casts, 1526 miss (9.65), 750 crit (4.74)

(4.33+3-X)*0.9012=4.74; X=2.07 [if only EP works, 4.07 if both do]

Test 4

Gear: 108 hit rating (4.12), 199 crit rating (4.33)

Talents: none

DC: 1758 44 crit

IT: 2650 46 crit

BB: 2610 52 crit

All: 7018 142 crit (2.02)

(4.33-X)*0.8712=2.02; X=2.01

Test 5

Gear: 236 hit rating (9), 539 crit rating (11.74)

Talents: none

IT: 5659 477 miss 482 crit

DC: 3982 335 miss 348 crit

BB: 5622 429 miss 522 crit

All: 15263 1241 miss (8.13) 1352 crit (8.85)

(11.74-X)*0.92=8.85; X=2.12