My 6-star R3 DDHK is sig 150, so that means I should take 90% reduced damage from Passive Degen and Direct Damage while Attacking in Stick’s Apprentice.
In the GIF below, I am taking full Direct Damage from Red Skull as I Attack in Stick’s Apprentice:

My 3-star R4 DDHK is sig 99, so that means I should take 100.01% reduced damage from Passive Degen and Direct Damage while Attacking in Stick’s Apprentice.
In the GIF below, after I transition from Murdock Boy to Stick’s Apprentice, I still take full Passive Degen as I Attack:

Not working as intended Kabam.