Illusionary Berserker has not received a direct damage decrease. Instead, is seems that the damage reduction you (and I) are seeing is most likely associated this fix:
“Fixed a bug that caused many piercing, boomerang, and bouncing projectiles (those that hit more than 1 target) to continually increase in damage the more targets they hit.”
We are aware that this particular phantasm is now experiencing a significant drop in damage and are looking at getting it back to a more effective state.
Thanks for keeping the post civil and constructive!
-Karl
Looks like there’s still hope for iZerker.