Storm is essential. Makes matchups against greedy Magik decks playable as well as comboing well with Morbius and Dracula easily winning the flooded location by themselves. Also helps the Thanos, Destroy and Loki matchups.
COUNTERS:
Doctor Octopus: Absolutely ruins this deck. For a small cost of losing wherever the Doc is played, it almost certainly makes Dracula useless and ruins discard sequences.
Rouge/Enchantress: For Morbius.
Phoenix Force: Discard can never beat this deck if they get the Multiple Man combo off.
Red Guardian: This card will destroy discard. Dracluas (and to a lesser-extent Morbius) are typically left solo in a lane until turn 5 or 6 so sniping them is highly likely, especially if a deck with Red Guardian is focused on getting priority early.