Whenever you discard one or more cards, target creature gets +2/+0 until end of turn for each card discarded this way. Whenever that creature deals combat damage to a player this turn, you draw a card.
Captain Howler turns discard into an aggressive engine: every discard pumps a creature and rewards connecting with card draw, so you loot/rummage aggressively to enlarge a threat (often Howler himself) and smash face for cards. You spend the early turns developing cheap evasive bodies and discard outlets, then snowball through repeated combat draws while looting feeds reanimation or madness payoffs. Most games end via an oversized evasive attacker or a combo built on the card flow.
Self-sustaining card advantage—discard pumps and connecting refills your hand
Cheap to recast at 4 mana and protected by Ward, making it resilient
Pairs naturally with Izzet's deep pool of loot/rummage and madness/reanimation payoffs
Turns discarded cards into immediate value, smoothing card economy.
Add evasion enablers (Rogue's Passage, trample sources) so the pumped creature reliably connects, and tighten the discard suite toward instant-speed outlets like Thrill of Possibility for combat surprises. Layer in payoff engines—Bone Miser, Rielle, Glint-Horn Buccaneer—to make each discard generate value beyond the pump. Round out with efficient interaction (Counterspell, Pongify) and ramp/cost reducers to consistently recast Howler and abuse Ward.