Well I killed 4 bosses on HC yesterday so I can try to be of some help if I can:
Goroth: I use demonic circle around middle to instantly return to some pillar to hide after moving the debuff away, and use portal between 2 quadrants of the room to help others change sides when the quadrant of the floor gets dirty
Inquisition: I use demonic portal in the middle back, to quickly avoid debuff zones and not get stacks of torment and also to move debuff away for a dispel. personally I used portal to help tank mindlessly kite the whirlwind of the boss
Harjatan: used both on the side to help me and others drop debuffs on the side of room
Sisters of the moon: Invaluable! Used circle to one edge of room to quickly swap debuffs, and portal connecting one edge to the other to help myself and others with debuff swapping again.
Mistress Sazhine: just had a few tries , even though risky if u fk up, u can use circle to troll the tornado, move forward then tele behind them, ignoring the mechanic that needs u to kill add to have the slime that blocks the tornado
will try to give u more insight tonight after raid