Sorath will use his reaction to counter spell. Going to roll 14

Thumbtack uses her reaction to Counterspell Sorath's Counterspell using her Ring of Spell Storing.

Lol yes this is all I wanted, counterspell fight.

Dan will use his reaction to counter spell. Going to roll 6

Lol ua the spell fizzles 

If it's going to be high-level spellcasters slinging powerhouse spells, how can it not be a Counterspell battle?

In the interests of fairness, Thumbtack's Counterspell from the Ring of Spell Storing is only at 3rd level.  So Dan's Counterspell automtically succeeds without a roll.

BUT, Casey can now Counterspell Dan's Counterspell using her reaction.

Hoping that is then the end of it since then Sorath, Dan, Aino, Casey and Thumbtack will all have used their reactions.  Garmuk can't cast spells while he is raging (even if he has any spells).

Ah did not realize that sweet the fight continues 

I was trying to figure out whos turn it was until I realized that everything that happened was on Sorath's turn lol, took me a second

Casey counterspells using 3rd level slot.  :). Aino turn..

Yep, all on Sorath's turn!  If you read the description of Counterspell - it works automatically if the spell you are trying to block is the same level or lower as the level you are casting Counterspell.  Otherwise it's a Check (not a Save) using the counterspeller's spell-casting ability (DC 10 + the spell level being countered).  That is why Aino used an 8th level slot to Counterspell Maze, which is too devastating a spell to take a chance.

Side note:  since it is a Check and not a Save, when Casey is Counterspelling, if she has to roll, which she wouldn't here, she could also add half her proficiency bonus rounded down (so +2 extra) to the Check due to Bards' Jack of All Trades capability.  Bards are the best Counterspellers if they take Counterspell as part of their Magical Secrets (Bards have no access to the spell otherwise).  Stone of Good Luck (Luckstone) also adds +1.

Aino and Thumbtack's turn (their reactions reset at the start of their turns):

Speaking of Maze being a devastating spell... Aino reads the Scroll of Maze that she had bought.

Casting it on Garmuk and maintaining concentration.  Sorath and Dan have already used their reactions, so they can't Counterspell the Maze, and Garmuk is raging so he can't cast spells.  Aino looks at Sorath innocently.  "Is this what you were trying to do?"

NO SAVING THROW (so legendary resistance does not apply).  Spell automatically works if not countered.  To escape, Garmuk has to wait until his turn and then use his whole action to try to escape, losing his Rage in the process.  Again, NO SAVE.  It's a DC 20 INT Check using his whole action to escape.  No benefit from Bless or Cloak of Protection or legendary resistance because it is a CHECK and not a SAVE.

With the effect of Haste on her from the Potion of Speed, Aino gets one extra action, though it is very limited in terms of what she can do with it (see the spell description).  Thumbtack does a Flyby of Dan, flapping wings in his face to take the Help action.  Aino tries to stay within 10' of where Storm will be when he moves forward to attack on his turn so she stays within the Paladin's auras.

With Garmuk gone, Aino talks to Dan while she attacks him, knowing the wound will probably only be minor.  "Dan.  Listen to me.  You can see what Garmuk has become.  There is some fiend inside him.  You cannot in good conscience support him the way he is.  Has something possessed him?  Call a truce and we can all dispel it together.  Or we can spar as we're doing now and help each other up afterwards, but do not give in to Garmuk's madness.  Right now, he is as bad as the Syndicate if not worse."  She is counting on Casey to do most of the persuading, but trying to set the groundwork for it.

Attack 1:  (Aino's only attack this round - this is the extra attack from the Potion of Speed, at advantage due to help and best of 3d20s due to Elven Accuracy.  Just straight Rapier, +3 since she can't cast another spell like Green Flame Blade.)
Rapier, +3 To Hit:  29 + 4 from Bless (Potion of Heroism) = 33
Rapier, +3 Damage:  24 magical piercing (max from 1d8+16).

(Waiting to see if Garmuk is banished before casey acts) 

Garmuk Vanishes 

Dan is hit.

Dan: We all have our reasions love and no offense I rather go with the demon I know vs an unknown. 

Casey is up

Casey soars around the arena on her griffon, and yells “Well,  looks like Garmuk is not here for a bit, so why don’t we work it out?  Mayhap you really don’t want Garmuk either.   Join us,  fight Garmuk and his supporters and together we can make things better for everyone.” Casey says, as she casts mass suggestion, strumming a chord on her Bandore as she does..     DC 22 wisdom save with disadvantage from her Bandore (charm effect).

she targets Dan, Sorath, and up to 10 obvious Garmuk supporters in the crowd, asking them all to “Join the side o’ the last Copper and ensure Garmuk is defeated”

if one makes the save (and the silvery barbs that comes after from the owl) she will target that one with (BA) Hexblades Curse (more damage when she attacks) and then swoop in and chuck her dagger at that one (extra haste attack) for 20 to hit, 11 damage if hits.  

As stated above by Tesservett, Thumbtack uses her reaction and Ring of Spell Storing to cast Silvery Barbs IF Sorath or Dan succeed on the save against Mass Suggestion to force a re-roll and give advantage to Storm's next d20 roll.  If both succeed, priority on Sorath.

Through Rary's Telepathic Bond, since Aino too knows Mass Suggestion:  Remember, do NOT damage anyone charmed, that breaks it.  Not just any damage, but if any of US damage them, then the effect of the spell goes away.  Target those who succeed and aren't affected.

Ok so Dan cant be charmed and Sorath normally would have advantage but will roll stright. And the 8 others in the crowd can only pass with a nat 20.

Sorath rolled a 21 so he fails. All in rhe crowd fail.

Dan: I already told you we all have our reasions

Sorath: I don't know Dan, Garmuk has gone a bit extreme even for me and that's saying something. Maybe it's time to give it up ya know.

Storm is up

Storm looks at Dan and points his sword at him "I see evil in Garmuk, perhaps you should look at your reasons again and weight them!" With that he commands his griffon forward into melee with Dan.

Griffon Move: Moves into melee with Dan

Storm Bonus Action: Hunters Mark on Dan, extra 1d6 damage on weapon hit attacks

Attack 1 w/ Adv from Thumbtack: 36 Damage: 22 Slashing + 19 radiant + 13 Necrotic (Spent charge from tattoo, Storm also heals this much)

Attack 2: 34 Damage: 17 Slashing + 15 radiant + 9 necrotic

Haste Attack: 30 Damage: 18 Slashing + 10 radiant + 15 necrotic

Storm Total Damage: 57 slashing + 44 radiant + 37 necrotic = 136 

Griffon Beak: 18 Damage: 14 piercing

Griffon Claw: 19 Damage: 14 slashing

Griffon Total Damage: 28

Forgot this earlier, Griffon Haste Attack: Nat 1, good thing it was its last attack

I want to add that during Storm's turn, Dan still can't use reactions.  This is because he already used his reaction on Counterspell during Sorath's turn earlier, and Dan's reaction does not reset until the start of his own turn which is next.

Dan is immune to radiant damage but it doesn't matter. Dan is toast.

Dan an charismatic host who's glory days are behind him can't withstand the vengeful fury of Storm. The Storm that is storm crashes overtime and he crumples.

End of the round.

Garmuk is up. Some stuff happens yall can't see.

Garmuk reappears. He sees Dan on the ground.

Weak fool. He will serve better in death then life.

Garmuk re-enters hus rage. Growing in size and turning red again. His eyes fix on Aino.

He attacks 

Attack 1: 34 to hit 18 damage

Attack 2: 35 to hit 26 damage

Attack 3: 28 to hit 17 damage

He will then use a legendary action demons reserve he gets to attack again with advantage but all attacks against him are also with advantage till the start of his next turn.

Attack 1: 31 22 damage

Attack 2: 26 22 damage

Attack 3: 32 18 damage

Sorath is up.

Sorath: weak fool? They are right you have lost yourself completely haven't you? I can't do this anymore you are not the Orc you once where.

Sorath turns to the party. I'm sorry you where right. You must stop him. he sold his soul to the eldet God Void in exchange for power. To kill Garmuk wont stop him you will have to kill the voidling posessing him as well.

Im going to take Dan and go Good luck.

Sorath and Dan's body teleport away.

The 8 people in the audience you charmed jump into the arena to help you. They charge are Garmuk and attack. 2 hit for 7 damage. Garmuk's evil aura quickly over powers all 8 of them and they fall to the ground dead.

The crowd is starting to feel this fight might get out of hand. A few start to leave but mist keep chearing on.

Order: Garmuk, Aino, Casey, Storm

Aino is up  

Before Aino's turn:

Garmuk's rage ended if he had to re-enter it.  So since he used frenzy last round, he suffers 1 level of Exhaustion.  All ability checks at disadvantage.

Leaving Maze takes an action (DC20 INT check), so normally that creature would NOT get to attack on their same turn as Garmuk is doing since they already used their action to find their way out of the Maze.  Would be true even for a minotaur or goristro demon who succeed automatically.

But I guess we're hand-waving that here because... elder gods?  This makes Maze, an awesome 8th level spell, completely useless.  It's one thing to succeed the DC20 INT Check automatically.  Here, Garmuk gets to leave the Maze AND still take his full turn (plus legendary action).  Ok.

Aino casts Shield as a reaction.  Her AC goes from 29 to 34.  All three of Garmuk's legendary attacks MISS.  Two of the three regular attacks hit, but Thumbtack casts Silvery Barbs as a reaction on the 35 for 26 damage, forcing a re-roll and granting advantage to Casey's next d20 roll.

Aino takes the 18 damage and I'll wait for the re-roll of the other attack (again, Aino's AC is 34).

DC10 CON Save for Aino to maintain concentration on Maze:  26 + 1 + from Bless and Aura for a 32 but it doesn't matter as she doesn't need to keep concentration on Maze any more anyway.  Apparently Garmuk can just bypass the action economy rules on Maze.

Like I said, I'll wait for the re-rolled attack before posting Aino's turn.

(Sorry your upset I guess i should have explaned what happened, No hand waving, I had to burn all of his legionary bonuses, his first action to make a move out of turn and a resistanceto pass a check he failed, thus he reentered the fight at the start of his turn.)

Re roll 29 to hit. 13 damage