For a warlock, you need a rod of reaving in one hand and a rod of corruption in the other. Together they can wipe out a whole gaggle of minions with a minor action, without even rolling to hit!
Curse the nearest one -- which causes 1 damage, which kills it, triggering your pact boon. Use that to spread your curse to all the others nearby (including the ones who are hidden from your view), which causes each of THEM to take 1 damage... which would presumably trigger your pact boon AGAIN.
Does this actually work? I was under the impression a character could only utilize the effects of one Implement at a time.