Serpents as minibosses

I suggest a snake-like miniboss mob that spawns naturally, although rarily, in all biomes. They can differ in size, colour and type and would form a challenge for the player, which should be rewarded according to the difficulty of the fight. They would consist of multiple segments that allow a smooth slithering motion. Only some segments would be considered vulnerable and can be attacked.

Different types of serpent include:

thorny) deals damage to the player when hit in specialised thorny segments

magma/nether) leaves a trail of fire after it and is resistant to fire damage

flying) can fly and applies levitation effect to the player whilst attacking

aquatic) spawns in bodies of water and drags players down

titanic) extremely large ( each segment is around 2 blocks tall ), only spawn in open oceans, deals 10 hearts of damage without armor, but is also the rarest type. 

Drops:

I suggest each serpent drops their specific head when killed, these are decorative, just like the dragon head.

Minecraft should include serpents as unique challenges for players, as almost every serpent will be different. 

Extra:

I suggest that the spawn rate of serpents be linked to hew well a player is equipped.

Serpents could slither around trees

The titanic serpent might jump out of the water to attack players flying with an elytra.

A serpent should be somewhat consistent with its biome, a nether serpent shouldn't spawn in a snowy biome