Fetus

Fetus is a ranged Sewers and Caves enemy that lobs slime shots up to 2 tiles away and heals itself by drinking from adjacent water tiles. As a familiar, it fights on the player's side with the same mechanics, providing reliable chip damage and self-sustain in wet environments.

The Fetus familiar's water-drinking heal makes it self-sustaining in water-heavy environments like the Sewers. It will seek out water tiles to restore HP between attacks, potentially staying active for an entire long battle without dying. Its 2-tile ranged slime attack lets it contribute damage without entering melee range.

In Sewers-heavy runs, the Fetus familiar can be one of the more durable companions available thanks to its passive water healing. Place it near water tiles and let it alternate between shooting at enemies and healing. In dry chapters it loses the healing mechanic but retains its ranged attack, making it a serviceable but less impressive damage familiar.