Owlboy

Story related and cannot be missed.

After infiltrating the pirate ship and stealing the relics, you'll have another boss fight. Try to aim at the boss and shoot with Twig to counter his projectiles, then dash at the same time when he's getting white to avoid being hit, then shoot him with Alphonse when he's catching his breath. For the last part, you won't be able to counter his projectiles; instead, you need to dash when he's moving right and left to avoid being hit, then kill him with Alphonse when he's on the ground.