Arius, Flyby Trawler is a rare Legendary Creature — Shark Pirate card from Alchemy: Aetherdrift (YDFT), collector number 21.
Flying, Trample Whenever Arius attacks, seek a non-Shark card. Discard that card at the beginning of the next end step. Whenever you discard one or more cards, put a +1/+1 counter on Arius.