Amatsu mh (Great TPK material)

Celestial fury. Sometimes gets angry after taking large dmg or when its weakened (dm decides when) it can add its ability mods 1 extra time to dmg(e.g. ×3 str dmg becomes ×4) and save DC increases by 1, its movemeant goes up by 5ft and its Elegant Evasion goes up by 5ft for 3-5 (dm chooses) turns, BUT while angry its chest glows brightly and becomes vulnerable to dmg buuuut you have to be facing it almost directly head on to target this weak spot, when it enters rage it uses its eerie cry feature.

Hurricane. It is surrounded by a hurricane at all times, when its alert (almost all the time and for about a month after it arrives) its hurricane is at f5 level stuff making it hard  to get to this creature, once threatened its hurricane will make escape almost impossible meaning the players will die if they cant escape... teleportation to other realms etc will work tho. Its up to the dm to deside how the players will get to amatsu, it will be almost impossible walking through it and flying is suicide but a cave leading under it that opens in the eye of the storm is a good idea.

Divine Dragon Resistance. 3 times a day, can choose to succeed if it fails a save. Enemy creatures like dragons have disadvantage on saves directly against amatsu and amatsu has advantage to hit them... (due to being a similar creature to amatsu it is much harder to avoid its atks, amatsu is likely experienced in fighting other kinds of dragons and monsters, but you can still get away with polymorph, its just not going to be game breaking), amatsu gains resistance to a number of elemeants of the weather like lightning, its also resistant to radient but weak to necrotic and poison with disadvantage against poison.

Makes one atk: slash or tail atk re every 2 atks e.g. slash, slash, tail atk.

Aerial slash. Melee Attack: +13 to hit, reach 10 ft., multiple targets within 10ft of its sipe. (3d6 + 12 (×2 str mod)) slashing damage. 

Tail attack. Melee Attack:  dax save DC18 range 25ft line 10 ft wide (3d8 +12(×2 str mod)) blugeoning damage. Recharge every 2 atks.

Zoom attack. Zooms 60ft in a line at the end of an enemies turn re 3 atks dex save DC18 2d6+ 7 (×1 dex) blugeoning damage. As bonus action.

Compressed water beam. Recharge Every 3 atks, fires 2 beams (eatch in different areas/targets up to 240 ft away) 60ft line 5ft wide dex save DC18 8d8+20 bludgeoning damage and knocked prone + on fail stunned, if proficient in fighting large creatures can expend half movemeant of next turn to gain the effects of evasion otherwise already having evasion will only negate stun and half dmg on a fail and success but still prone for either.

Tornado tpk. Re 8 Expends 3 turns of focus during witch enemies are sucked in at 20-25-30 ft each turn and are unable to dash + must make a athletics check in order to move half movement and half atks otherwise they cant move at all or atk normally, if anything is within 15 ft of amatsu at the start of its 4th turn takes 20d8+ 100 blugeoning damage dex save or athletics check DC22 for half dmg as the blast has a split second delay, if you have 40+ movemeant speed than a success equals no dmg as you manage to leap away but you are prone after this. Ps  attacks made by ppl affected by amatsus pull affect have disadvantage. Also anything within 10 ft of amatsu during its pull affect auto fail checks/saves to resist and move away so they are in trouble. As this atk triggers it releases an eerie cry (this doesnt have to stun players) and circles the space underneath it at super speed a split second later a crystaline jingle rings in the air and the spot explodes into a tornado with wind speeds on steroids for a few seconds till the end of amatsu's 4th turn, amatsu cant take any atk actions on this turn it can only move or at most use its zoom as it will be near the edge of the arena after this. Optional can choose to give amatsu resistance to dmg while doing a charge up for this atk, but ignore this if its too hard.

Tip use dice and set it to the number of turns or atks till an ability recharges. Or just right it down.

Elegant Evasion. Can move 15ft out of the way of an incoming attack, if it only just gets hit it take half dmg, grants the effects of Evasion, so AoE doesnt work so well against it unless you aim at the ground tho! Costs 1 legendary action.

×3 actions a round. Can only take 2 options per round.

Zoom atk (Costs 1 Actions). 

Elegant Evasion (1 Action)

Eerie cry (2 actions and 5 turn cooldown) lets loose a cry that requires a wisdom save DC17 or be frightened for 1min can repeat saves at start of turn etc once this effect is endded the creature is immune for 24hrs, additionaly creatures must make a constitution save on a fail they are stunned, this effect only works if you are within 80ft of amatsu DC15 70+ft 16 60+ft 17 40+ft 19 1+ft, or just use 16 if you cant be bothered with this table.

if it drops below 60% hp (1440)it gains extra attacks, speed, dmg and moves. It should use its tornado tpk at this stage, it should use it atleast twice during the battle.

+10 ft movement, +1 atk gains enhanced atk options, DC of 18 increases to 20.

Swipe and tail actions gain ×3 str (+18) 4d6, 4d8

Zoom gains ×2 dex (+14) 3d6

Water beam+ same as the original but 120ft line 10ft wide8d8+42 every 5 turns, flys into the air emmitting a loud cry, just before the attack a crystaline jingle rings in the air.

 Tornado burst. Takes 1 turn to charge, at the start of next turn Shoots 4 tornados in 4 opposite directions, they travel 80ft a turn and last 2 turns, eatch tornado is a 20ft sphere, on contact a player is knocked flying 30ft away and lands prone but if the tornado just clips you make a dex save DC18 success no dmg fail half dmg knocked 10ft and fall prone, the dmg is 4d10+20 bludgeoning.