Don't start serious swarming until you're within a few zones of your opponent so that you can get at and destroy any anti-swarm conjurations like Idol of Pestilence that they play. Deathlock isn't really a problem so long as you don't overcommit to healing. If your opponent drops a turn 1 Idol of Pestilence, either go with a Steelclaw Pet or a Steelcalw and a Timber Wolf Pet, and don't swarm. They're resilient enough that Idol of Pestilence won't kill them quickly, and they can do a lot of damage quickly, particularly supported with Bear Strength and Battle Fury. As long as you don't overcommit to a swarm, you should be fine. It may end up being advisable to destroy the Idol of Pestilence when you get the chance, but often it ends up being better to just focus down the Warlock. Remember that he's hurting himself too, and he devoted mana to it, which means that if you haven't invested in any level 1 creatures yet, you can easily come out ahead. Idol of Pestilence is approximately a full round of channeling for a Warlock.