Just a warning, its not very useful, but its fun since you can group with your original faction but fight for the opposite.
- Queue for ashran as merc in underbelly.
- Once in ashran, die either using unstuck(need to delete your HS or it will use it instead) or just let opposite faction kill you.
- (Important) When you are spirit, waiting for the gy rez, select to leave the Ashran on the green icon.
- It will say cannot do this while dead or something like that.'
- Now you are in Ashran without group and it will let you stay for as long as you want.
- Go into PVP ui, queue for normal Ashran without merc mode.
- Once its about to port you in(it actually won't since you are already here), you'll just join the opposite faction raid group while still staying as the merc mode.
Again, not very useful as you only get credits from your merc side and non from raid group.