Inquisitor (20) with:

Equipment:
Thunder Hammer (25), bolt pistol (1), power armour (10), frag grenades (1)

Psychic Powers:
Holocaust (15)

Henchmen:
3 Acolytes with Storm Shields (54), 3 Warriors: Weapon-Servitors (30) with power fists (45),

Cost: 201 points

Abilities:
Defensively, this Inquisitor is very strong, as aside from his 4+ Invulnerable save in close combat, any hits can be transferred to an Acolyte. Each of these chaps has a 4+ Invulnerable save in close combat. The enemy makes their attacks, which are countered by the Inquisitor or his storm shield Acolytes. At the end of the round, a potential 9 power fist attacks and 3 Thunder Hammer attacks pile in, plus a Strength 5 Ordnance Blast hit from the Holocaust power. This should be enough to deal with any opponent, elite or swarm.

Tactics:
Get these guys into the thick of the fighting, preferably against an elite opponent such as Space Marines, or even better a Tyranid Monstrous Creature where the power fists can really make themselves useful. When fighting a swarm army like Orks or Tyranids, position the Inquisitor so that his Holocaust power can catch as many models as possible.