I don't often use parasites, so it was fun building decks around them. Several good suggestions have already been given, but here's an alternate build I've been playing around with:
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52r 52r 52r 542 542 542 542 542 542 542 542 542 542 5uk 5uk 5uk 5ul 5ul 5ul 5un 5un 5un 5un 5up 5uq 5ur 5us 5us 5us 5us 8pt
For defense it abandons the vamps in favor of trusty bonewalls + lots of CC. The drain lifes are for targets that need to be killed quickly, and because the parasites offer repeatable CC to either spam and keep hordes at bay, or focus fire to bring down the toughest creatures. The dragons and nightfall come in to help punch through damage reduction shields.
The dusk mantle is of course dropped in favor of the bonewalls, and the Liquid Shadow, Nightmare, and Cloak were also removed because they don't have enough synergy with the rest of the deck to justify their inclusion. The steals I felt bad to remove, because they are such a useful and fun card, but steals and bonewalls don't mix very well, and I needed to keep the deck relatively focused or the combo might come too late or without enough CC strength. I increased the number of quanta sources to better balance the deck and give the Drain Lifes enough quanta to start doing additional damage earlier.
Hope some of this was helpful, if at least as food for thought.