(ok we will say time passes and you are now about 200’ away, if that works)

Initiative:

 Casey, knight, Tarrasque, aino, Storm, Jarn

casey flies above the Tarrasque, and uses her Hexblades curse on the knight, then shoots 4 eldritch blasts at him, hitting 4 times for a total of 76 damage…

she rises her pegasus swooping in formation near Storm.

The knight points his arm at casey and reaction  casts hellish rebuke on her, she makes the save so takes half of  28 damage - further reduced by her buffs. 

he then casts darkness  and uses second wind.  13 

a 15’ radius ball of inky blackness appears on  top of the Tarrasque.  

The Tarrasque destroys a farmhouse, chomping down several cattle, oblivious to what’s happening on its back. 

aino up. 

Unless you can see inside the darkness spell, the knight can’t be seen.   The Tarrasque is there but hasn’t noticed the group yet.

 The darkness is just on the top of the tarrasque around the Howdah.  The tarrasque is now about 120 feet away from the group.  (It is Moving very fast) 

  aino, Storm, Jarn up, then casey. 

Couple questions:

Are we actually starting closer than 200'?  How did Casey get within 30' to put her Hexblade's Curse on the knight in one turn?

Aino as part of her preparation cast True Seeing.  So her resulting 120' truesight makes the darkness a non-issue for her, right?

(You can start where you want-  it has to do with where you used your short duration buffs.   I had this idea that maybe someone would do something else if it was a little further away.  but Casey can fly at 180’ on her pegasus hasted)

yes true seeing penetrates the darkness.   You see he’s still on the platform. 

Ok sounds good.  Aino and Thumbtack will start 60' above the knight split apart.

The Darkness still affects Aino's allies, so let's resolve Casey's and the Knight's turn first.

With her reaction on Casey's turn., Aino Counterspells the Knight's Hellish Rebuke.  (If it is a spell that can be countered and not somehow innate?).  She uses her 20th level Signature Spell feature to cast it without using a spell slot.

With her reaction on the Knight's turn, Thumbtack Counterspells the Knight's Darkness using her Ring of Spell Storing.

Yes both can be countered.  Casey says “Thanks fer that!”   He’s already used his reaction.  

Quote from Tesservett >>

The knight points his arm at casey and reaction  casts hellish rebuke on her, she makes the save so takes half of  41 damage - further reduced by her buffs. 

he then casts darkness  and uses second wind.  13 

a 15’ radius ball of inky blackness appears on  top of the Tarrasque.  

 OOC: Unsure where on Caseys turn the Hellish Rebuke occurs but remember that if within 30 feet of Storm, due to Circle of Power, if anyone makes a save that would result in half damage they instead take none.

OOC: Want to make sure Im not holding things up, its Aino's turn right?

Yep, Aino's turn, but dndbeyond not bringing up character sheets for me over the last hour.  It's ok, though, I think I can post this turn without it.

(Guess the Counterspell on the Hellish Rebuke was a waste as it would have done no damage anyway?)

Aino and Thumbtack's reactions reset.

Also 60' above the Tarrasque on her Broom of Flying, Aino reads her scroll of Maze, targeting the Tarrasque.

• No saving throw (so legendary resistance does not apply)
• Tarrasque instantly disappears for up to 10 minutes or until Aino loses concentration on Maze or the Tarrasque finds its way out.
• Presumably the knight and the platform crash to the ground (unless he can fly), visible to everyone as the Darkness was Counterspelled.
• Escaping the Maze requires an Action (not a legendary action).  DC 20 INT Check (NOT a Save, so again, legendary resistance doesn't work).  Also, saving throw proficiency does NOT work as it is a Check, and not a Save.  So straight, non-proficient INT check for Tarrasque to escape, DC 20.
• Clearly, if the Knight attempts to Counterspell, Aino will use her reaction to Counterspell that if Casey does not.  (She'd prefer Casey to do it so she can keep her reaction for Shield in melee if necessary).  As far as reactions go, I think the Knight used his reaction on Hellish Rebuke on Casey's turn, but then his reaction reset on his own turn.

Aino descends if necessary to be 30' above the Knight's head.  No bonus action (or perhaps it was just used to start her bladesong).

Thumbtack continues to fly, also descending if necessary to be 30' above the fallen Knight's head, taking the dodge action.

Both try to stay within 30' of where Storm will end up.

OOC: Once I know how Maze worked out I will post Storms turn

Wow.   The knight attempts to counterspell, which is countered by casey, and so the tarrasque disappears and is in the maze.  The knight can’t fly, so he falls, taking 19 damage and is prone. 

Storm up!  

Storm grins as the Tarrasque disappears and the Knight falls to the ground vulnerable.  He urges the griffon forward and unleashes his fury "Your path of terror ends here!"

Griffon Move: Next to knight

Attack 1: 21 Damage: 15 slashing + 7 radiant

Attack 2: 29 Damage: 17 slashing + 16 radiant

Haste Attack: 19 Damage: 12 slashing + 11 radiant

Bonus action: Shove attempt via Shield Master, Athletics: 13

Griffon Action: Dodge

Griffon Haste Action: Disengage upwards to be out of melee range (Griffon has 160 ft fly speed with haste so unsure how much was used to get into melee)

Trying to figure out what to do. Never played a lvl 20 before I'll post later tonight

Jarn follows Storm to the knight. And kicks him whiles he's down.

Attack 1 with short sword 32  Damage 12 piercing 

Spend 1 Kai pount to stunning strike

Stunning Strike (Special)

When you hit with a melee weapon attack, you can spend 1 ki point to make the target stunned until the end of your next turn if it fails a CON saving throw (DC 19).

Since Storm is within 5 ft sneak attack applies I believe. Damage: 8 damage

Attack 2: nat 1 miss

(If your doing Nat 1 ends turn I'm done if not see below)

Spend 1 kai point to flurry of blows as my BA.

Attack 1: 31 damage: 13 

Attack 2: 24 damage: 12

Sum of 20 damage plus the consave DC 19 or

45 damage plus the consave

OOC: Sorry I forgot advantage when they are prone, please see below for the actual hit rolls. And that also means Jarn has advantage on his attacks as well.

Attack 1: 28

Attack 2: Stays at 29

Haste Attack: 34

Bonus action to shove: I forgot he was prone so will not actually do that afterall

Ooc: thanks also forgot my haste attack.

Attack 1" stays at 32

Attack 2: 30 damage for 10 damage 

Hates attack: 24 for 14 damage.

Flurry of blows

No change to the 31 and 24.

So new total damage if all hit.

69 damage (nice) plus the DC 19 con save

(Sorry for my slow posts. Will catch up tomorrow!)