@OmniStrata Withering Wisps is Pestilence on steroids and I think it fits well into the deck's philosophy. It also combines well with Nether Spirit - return Nether Spirit at the beginning of your turn, cast some discard/sinkhole spells, pass the turn, activate Withering Wisps at the end of the opponents turn. Lather, rinse, repeat. For this build I'd prefer to have some life drain effect so we always have more LPs than our opponent. I'd recommend another cool card from Ice Age -
Soul Burn as it is a great thematic addition to Pox, Scyring Sheets, Withering Wisps, and Snow-Covered Swamps, but
Drain Life is better (and a Mirage reprint has an amazing art by RKF).