I have a stripped character

The only damage increase I have is from DEX which is exactly 500 for a 50% increase

I have no damage increases from gear or paragon or passives

My weapon damage is 4086

Rank1 penetrating shot says it does 70% of my weapon damage

Rank1 poison imbuement says it applies 100% of the base damage

I am level 100 hitting a level 100 target dummy so there is 74% monster DR

So an imbued pen shot is expected to do:

Weapon Damage * Pen Shot Damage * Poison Imbuement * DEX Multi * Monster DR

4086 * 0.7 * 1.0 * 1.5 * 0.26 = 1115 damage

When trying this on the dummy I am getting 10 ticks of ~110 so this is working as intended

What confuses me is when I use an Andarielâ€™sâ€™ Visage

The tooltip damage shows 24515 which is 600% of my weapon damage

The expected damage is:

tooltip damage * DEX Multi * Monster DR

24515 * 1.5 * 0.26 = 9,560

However it does 10 ticks of 3826 which is 38260 damage

Which is almost equal to the tooltip * DEX multiplier which is 36772

It is as if this damage bypasses the 74% monster DR?

EDIT:

The new patch changed something, the patch notes say 50% buff

Tooltip now shows 36773

The new expected damage would be 36773 * 1.5 * 0.26 = 14311

But it does a total of 38260 so the same exact amount as from before the patch

Also the nova visually appears around the target, but the damage still occurs around the player