In this situation I think nuking would be a bad idea. If the Warlock is SL/SL with decent resilience, you will not be able to burst him down. ESPECIALLY as BM. Say what you like, BM doesn't have burst damage. What it does have is really fast, medium damage.
The problem is that Druids are gods at healing in arenas. Their HoTs will greatly reduce your overall damage to the lock. When you couple this with the natural "Can't kill me!" of SL/SL locks, you will not be able to burst him down.
Thus, I'd suggest draining the Druid. Get a scorpid, train max nature and shadow resistance. Get Improved Stings (in the Marksman tree). Sick said scorpid on the Druid and Viper Sting him. Rinse and repeat. (It helps if you have Aspect of the Viper on)
What you need to watch out for is getting feared. You shouldn't be taking massive amounts of damage, but it will add up. If your pally is constantly feared, you will not get heals. I'd suggest your pally pillar-humps, only coming out to heal you. (Which I mean he should be doing anyways.) Make sure he doesn't blow his bubble stupidly, and also keep in mind that Blessing of Protection doesn't stop DoTs from ticking.
As an alternative, you *could* drain the Warlock instead of the druid. I'm not entirely sure if this would be more effective. Also, you need to watch out for the Warlock mana draining your pally.
Happy hunting!