if you wanted that, you'd need this list:
HQ - Grand master w/ retinue of 4 termies @ 329 pts
- Inq. Lord w/ sanctuary @ 76 pts (bare minimum, including sanctuary, bolt pistol and power weapon, but i'd suggest better wargear or henchmen to capitalize on what you aim to do. check the GW section on DH and look for inquisitors there)
Elite - 3x 4 Termies and 1 Brother captain @ 735 pts.
Troops - 2 x 4 Grey Knights & 1 Justicar @ 300 pts.
Heavy - 1 Land Raider @ 250 pts.
Total - 1690 pts
That would be interesting to see, but note that this list is the bare minimum (no wargear added with the exception of the Inq. Lord). 20 GK termies might scare some people senseless, but if they got plasma, melta or lances, you're gonna have a rough time.