If you try it in A3S, after your 3rd GK, you will have 3 GCD's left. Instead of applying HT, just do TTT. Then when he becomes vulnerable again, you can open with HT-IDC4-PH. This way you get higher potency right before he invulns, the Disembowel and CT will still be active the entire time through the invuln and into your second opener.