Charybdis:
The Charybdis fight would start with a moderate sized whirlpool spawning which is incredible hard to navigate out of and puts a lot of stress on your ship (causing holes for you to repair). Only an incredibly talented crew (especially helmsmen) would be capable of escaping.
If you fail to escape, you will begin to descend down the Charybdis long body. This would be like a decently sized river forward completely enclosed and rather dark. Instead of sailing on water, you are sailing on stomach acid, which will cause occasional holes (like storms) which pour in acidic water into your ship which causes damage (like boiling water).
Inside this path, there will be shipwrecks/rocks/teeth you have to dodge out the way off to avoid taking catastrophic damage, dodging these is intended to be difficult and it might require someone to deviate from a standard role and be on the harpoon guns to pull the ship out of harms way.
Along the way you will need to deal damage to weak spots on the Charybdis' insides (which appear as slight wounds / scars it has accumulated from it's long life). Attacking other spots will still deal damage but significantly less. As well the Charybdis might "gargle" and cause a shipwreck to be flung towards your ship which has Skeletons/Ghosts of dead pirates on which will attack you.
If you fail to deal enough damage quick enough and reach the stomach of the Charybdis or sink on the way, that will be the end of you.
However if you deal enough damage the Charybdis will spit you out alongside some other bits and bobs it has swallowed along the years (skulls, chests, barrels, etc.) and a big Charybdis tooth you can sell.
Phoenix:
The Phoenix is native to the Devil's Roar region, but the fight can be start anywhere. If you start outside of the Devil's Roar, the phoenix will pick your ship up by your main mast and fly you over to the region and drop your ship.
During the fight, the volcanoes around you have a much higher chance of exploding causing general chaos.
The Phoenix can do two main things to your ship. One being to drop volcanic rocks on you, causing damage, fire and holes in your ship (if dropped directly on a player, it will kill them in one shot). The other being to pick the ship up by a Mast and drop it, which will break the mast and cause a fire on it.
The Phoenix is a flying enemy and will circle above your ship for most of the fight, making it hard to hit, but it can't withstand much damage. The primary way of defeating the the Phoenix is to shoot it with cannonballs. If you hit the wings, it will be slightly slower and fly slightly lower for a temporary amount of time, making it easier to hit more shots.
You are able to escape the fight by leaving the Devil's Roar region.
When you defeat the Phoenix, it's body will drop and leave behind some Phoenix feathers and a map to a tomb of lost treasure nearby which will contain a lot of high quality loot.
