judging from the massive silver/negative effects on the blocker, i assume, the beast used his fury.
Just tested my beast against a red blocker in PVP: nothing unusual. Sure the other toons and the eddie take damage off the single attack from the beast, but that's normal. Plus your enemy has the yellow lilith, which does multiple damage in small hits. And as it's not considered as high damage, it's not getting blocked. (only damage above 50% off your life), so every damage below gets through.