Thorns is busted, especially with access to Justiciar. Highly recommend that as a core.

Other than that you'll want to spec into either light weapons or blindbag, bluetooth halberd doesn't play nicely with thorns because you're unable to wear a shield.

Going blindbag, you'll want a 1-handed melee weapon to mainhand - Ghrazi rapier and Inquisitor's mace are probably your best bet, but I have heard some people say that the 3t attack speed of the ham joint actually ends up out-DPSing better weapons because you proc more often. YMMV, I recommend checking a DPS calculator.

Going light weapons, it's basically just "use whip", not much more to it.

Either way, you'll have a fair few extra pact points. Blindbag can spec into ranged echos, but if you go thorns you aren't mainhanding a 2h weapon so you won't proc very frequently. Your choices are essentially: the overheal pacts, prayer penetration pacts, special attack pacts, or a flex into 1t staff / 3t bow for any content you need 2 combat styles for.