Inquisitor (20) with:

Equipment:
Consecrated Scrolls (5), Unguents of Warding (10), Psychic hood (20), bolt pistol (1) and close combat weapon (1)

Psychic Powers:
Scourging (20), Holocaust (20)

Henchmen:
3 Familiars (18), 1 Mystic (6), 1 Hierophant (8), 1 Sage (10)

Cost: 139 points

Effects:
The Inquisitor can either fire D6 S5 psychic bolts per turn, hitting on 2's (BS 5 due to the Sage) with no Invulnerable saves allowed or, during the Assault phase, place a large template in base contact for basic S5 AP5 hits. Once per game he can use the Consecrated Scrolls to do both in one turn. His Psychic hood enables him to potentially nullify enemy psychic powers, and if that fails, his Unguents of Warding nullify any psychic powers cast at him or his unit on a 4+. The Hierophant adds one to his Leadership, helping him to pass those important psychic tests. Because of his Mystic Henchman he can also use Scourging on manifesting daemons provided they are close enough.

Tactics:
Keep this daemonhunter relatively close to the enemy lines, so that when your opponent summons his daemons you can exterminate them with Scourging. Remember, you do not have to be in base contact with the enemy to use Holocaust, so you might want to coordinate an assault with one of your units plus the successful use of this power for maximum effect, especially against horde armies.