/--Initiative--/
21 - Hobgoblin E
20 - Kiersa
17 -  Minotaur (-22), Hobgoblin F, Manticore
10 - Maeve & Iravon
9 - Hobgoblin A & B
8 - Valeria
3 - Hobgoblin C & Creature W
/-------------/

The minotaur flexes his muscles, lets out a roar, shouting, "Vermin, be slain in Tiamat's name!" It rushes in a straight line towards Iravon, charging with its horns prominent. Kiersa's attacks land true, but the minotaur barrels forward regardless, uncaring. [It took the 22 damage, but it still looks pretty good. It is injured, but not bloody.]
Minotaur -> Iravon Attack: 20 Damage: 18 piercing damage vs AC 19
                 -> Bonus Damage due to Charging if above hits: 11 piercing damage (plus an additional 9 if crit). Iravon will also need to succeed a DC 12 Strength saving throw or be pushed up to 10 feet away and knocked prone.

A new hobgoblin enters the mix from the room up north! Like their brethren, they pull out a longbow and take aim at Iravon. After all, he clearly issued the challenge... It seems the hobgoblins are creating a formation and are pressing their advantage using the minotaur as the shield against what seems to be your initial assault.
Hobgoblin F -> Iravon Attack: Attack: 13 Damage: 3 vs AC 19 [If Iravon is prone, this attack has disadvantage which cancels out the advantage... I will just use the worse roll in this case.]
                       -> Kiersa, Iravon, and Valeria -- you all realize that hobgoblins work best as a squad. They always seem to gain advantage when they have allies within reach of their targets. This advantage can be used for melee or ranged attacks!

The thing Valeria [likely] feared the most is being realized -- she sees a manticore emerge from the room in the south! It lifts off the ground and doesn't spot Valeria, she is still invisible after all! Instead, it circles overhead, hanging around 50 ft up in the air and flings several tail spikes at Iravon and Kiersa! [It failed to perceive Maeve! Also, if Iravon is down, all go to Kiersa!]
Manticore -> Iravon Attack: 14 Damage: 7 piercing vs AC 19 [Has disadvantage if prone, which will be this roll: 10]
Manticore -> Kiersa Attack: 19 Damage: 7 piercing vs AC 18
Manticore -> Kiersa Attack: 7 Damage: Unable to parse dice roll. piercing vs AC 18

[Maeve and Iravon, you may take your turns. If Iravon is down, this is an example of using your turns tactically where Maeve could use Healing Word or something to bring Iravon up so he doesn't need to make a death save. This is all up to you guys. Sorry for assuming Iravon is down as I type this! I am sure he is fine since he is a tanky boy!]

Updated Map:

Mae will just peek around the corner of the building enough to see the minotaur, point at it (casting Message) and ask it why it is defending the Keep.

Thump, thump, thump, the minotaur's heavy hooves dig pits in the ground as it charges towards Iravon like a hairy boulder. Iravon judges his moment, and raises his shield as the minotaur lowers his horns. The two connect - the shield shudders, and vibrations run up Iravon's arm, but he holds, and deflects the massive head of the minotaur away. Past the minotaur's flank he spots a hobgoblin taking aim with a longbow, and again raises his shield, but without need - trying not to hit his massive ally, the hobgoblin sends the arrow whistling past Iravon harmlessly.

But shield, cloak and armour prove useless against the sudden spikes of the manticore he now sees flapping in the air above the keep, as one thick needle finds its mark. Iravon grunts in pain, and rips out the spike. Nothing he can do about the manticore, better to focus on what is right in front of him.

Facing down the minotaur, he swings hard with his flail, shouting as he does, "Maglubiyet!"

Flail: 11 Damage: 6 bludgeoning
Flail: 14 Damage: 9 bludgeoning

If at least one hits, add a Divine Smite 2nd level: 13 radiant

/--Initiative--/
21 - Hobgoblin E
20 - Kiersa
17 -  Minotaur (-50, Bloody), Hobgoblin F, Manticore
10 - Maeve & Iravon
9 - Hobgoblin A & B
8 - Valeria
3 - Hobgoblin C & Creature W
/-------------/

Maeve, the minotaur seems to respond to you in your mind, but you don't seem to share a language. Instead of replying with a whisper, it shouts, "There is a mage among them! Find the mage and destroy it!"

[Maeve, since this wasn't very fruitful for you, I will allow you another action if you'd like to take it. Think of it as an apology for taking so long to respond!]

The power of Maglubiyet flows through Iravon as he crushes the flail into the minotaur's skull. It makes an audible crack as the creature reels in pain from the blow.

Meanwhile... For Valeria's eyes only:

A hobgoblin (B) moves into position (J9) and fires onto Iravon, once again pressing its advantage. After its shot, it drops prone. [Ranged attacks against it are made with disadvantage.]
Hobgoblin B -> Iravon (Attack: 23 Damage: 12 vs AC 19)

[Valeria, it is your turn!]

(I'd just say let Mae Insight check the Minotaur's response: 21. She is trying to stay quiet and covered still.)

"Iravon! Kiersa! They have hobgoblin spellcasters. Try to fall back!" Valeria desperately calls out from then skies as new threats keep appearing, cursing herself for not being prepared better for this kind of opposition. She holds off from attacking but keeps a good look out for even more reinforcements she expects to join battle in a moment.
"Hey, I'm over here, try to catch me if you can!" She shouts at the manticore, hoping to distract it from Iravon and Kiersa.

Persuasion if applicable: 15

(End turn :-)

/--Initiative--/
21 - Hobgoblin E
20 - Kiersa
17 -  Minotaur (-50, Bloody), Hobgoblin F, Manticore
10 - Maeve & Iravon
9 - Hobgoblin A & B
8 - Valeria
3 - Hobgoblin C & Worg
/-------------/

Quote from Gnomesftw >>

(I'd just say let Mae Insight check the Minotaur's response: 21. She is trying to stay quiet and covered still.)

 For Maeve's eyes only:

Quote from Oberon99 >>

This post has potentially manipulated dice roll results.

"Iravon! Kiersa! They have hobgoblin spellcasters. Try to fall back!" Valeria desperately calls out from then skies as new threats keep appearing, cursing herself for not being prepared better for this kind of opposition. She holds off from attacking but keeps a good look out for even more reinforcements she expects to join battle in a moment.
"Hey, I'm over here, try to catch me if you can!" She shouts at the manticore, hoping to distract it from Iravon and Kiersa.

Persuasion if applicable: 15

(End turn :-)

 [Valeria, just to be sure, you are dropping invisibility? If so, is your action to take the dodge action or something like that? Will you move at all? Just checking! Random, as I was editing this post through, I realized, maybe you are still invisible and trying to get it to follow your voice. Just let me know what your intentions are so I don't mess this up haha!]

Hobgoblin (C) continues its barrage of arrows at Iravon! Again, pressing its advantage.
Hobgoblin C -> Iravon (Attack: 14 Damage: 2 vs AC 19 (or AC 21 if we accept RAW cover))

Meanwhile, it seems like suddenly from out of nowhere, a worg rushes to the front lines! It makes it through its allies [which eat up its movement] and pauses behind the minotaur. It's eyes flash red as it seems to scan the battlefield. It is incredibly aggressive in appearance, but it appears to be ready to take evasive maneuvers. [Aka it is taking the dodge action. Creature W is now revealed to be a Worg.]

[I am putting it here too -- as an apology and maybe a 'get out of jail' free card -- everyone may take a free turn right now! Then we will go back up to Hobgob's turn!]

(Then Mae will lightly brush the strings of her bandalore, look at the Minotaur, and cast Levitate. They can make a CON 15 save to avoid the effect.)

Valeria watches in desperation as more and more servants of the Red Hand swarm out of Vraath keep, the young noble almost turning to despair as her companions seems lost to the flood of enemies, when she suddenly feels a surge of power as if the goddess herself intervened to save her trusted servant in her time of need, making her briefly shine as the brightest star above the battlefield. With renewed conviction and determination, carried by her winged boots, Valeria then calls upon the divine powers of Selûne, uttering celestial words while making a quick pattern in the air with the fingers of one of her slender hands, the other hand touching her amulet to send a fiery star from the skies, roaring down to blossom with a low roar into an explosion of flame engulfing the courtyard in a divine inferno.

Kiersa, staying on horeback still, continues to attack the minotaur. (Hopefully before it is out of range if the Levitate works!)  
(Longsword Attack: 23 Damage: Unable to parse dice roll. slashing)
(Longsword Attack: 16 Damage: 9 slashing)

If Levitate works:

Iravon watches in surprise as the Minotaur lifts helplessly into the sky, confused and flailing. It must be Maevla, it seems like her kind of mischief. But it gave an excellent opening. As he made to move under the floating Minotaur a worg emerges from keep, and stands growling, tensed, blocking their way through. Iravon growls in response. He now wished he had summoned Dargrath before they approached the keep, but it was too late now. They would have to stand their ground.

He runs forward, his flail held behind him to maximise the swing, and as he does he bellows words of power. His flail begins to glow, as he swings it down on the worg with a shout.

Thunderous Smite: +9 thunder dmg to first hit, and STR save 14 or pushed 10ft and prone.

(1) Flail: 10 Damage: 7 (rolled with disad due to Dodge)

If (1) misses, or hits but it makes the save, second attack (2a): 9 Damage: 7

If (1) hits AND it fails save, Iravon follows it and swings again as it lies on the floor prone. Second attack (2b)(Assuming Dodge+Prone=straight roll): 17 Damage: 12

If Levitate DOESN'T work:

A Minotaur, a manticore, and now a worg? Iravon was not one to feel fear, but he could tell that the battle was turning against them. Even retreat, which he loathed, would not help - they were fanatics, and would hunt the party down, him especially. So, they had better start thinning out the enemy. He reels back his flail and prepares to finish off the Minotaur.

Keep Thunderous Smite as above. Attack rolls without ad or disad.

Flail: 23 Damage: 12

Flail: 15 Damage: 8

Blimey, I think we need a flowchart for all that...

Following the Levitate route, the first attack (1) clearly won't hit, and without metagaming and checking worg stats I'm not convinced (2a) attack will hit either, so I'm going to invoke Saving Face racial trait. Iravon can see Kiersa and Valeria (or if she's still invisible he at least knows she's up there watching, if DM allows that to count), so if (2a) comes into play but doesn't hit, please add 2 to the attack making it 17.

Tring to preempt all the outcomes is @_@

[Tee hee, my son had a 101+ fever on Monday and spent all Tuesday being ill. FINALLY... I am updating. Rolling dice for reasons.]

1

17

4

5

13

19

9

17

19

14

/--Initiative--/
21 - Hobgoblin E
20 - Kiersa
17 -  Minotaur, Hobgoblin F, Manticore (-29)
10 - Maeve & Iravon
9 - Hobgoblin A & B
8 - Valeria
3 - Hobgoblin C & Worg
/-------------/

Valeria's fiery star shatters over the battlefield, devastating the hobgoblins. None of them survive the blast. The worg, fresh into the battle, falls. The only things left are the Manticore and Minotaur. An odd pair to be sure, and even odder still to consider they are aligned with these fallen hobgoblins.

Maeve weaves a spell in the chaos, causing the minotaur to lose not only its center of gravity, but its very tether to the earth. Iravon sees this opening [its dodge negated in this instance by the levitation I'm ruling] and crashes the ball of his flail into the creature. Kiersa, likewise, strikes while the poor creature is floating against its will. It takes them both, but the creature is indeed dead.

Now all that is left is the Manticore...

[Kiersa's turn again!]

With so many of the enemy falling, Kiersa spurs her horse forward quickly, heading for the manticore.  Somewhat circling around it, she finally closes in to attack. (Moving to F14. Should have plenty of movement to get there.)

She slashes down twice with her longsword as she drives towards the manticore.

(Longsword Attack: 23 Damage: 9 slashing)

(Longsword Attack: 27 Damage: 10 slashing)

(OOC - forgot those should have been with Advantage, but think they might have hit anyway.)

(Not to spoil things, but isn't the manticore like, 50ft up in the air?)

Quote from Gnomesftw >>

(Not to spoil things, but isn't the manticore like, 50ft up in the air?)

 (Yes, it seems this is true. Been a while and lost track of that. I'll redo Kiersa's turn then. Should I delete the posts?) 

With other enemies now defeated, Kiersa sheathes her longsword and draws her crossbow.  Staying atop her horse, she moves a bit north (to O8).  She fires at the manticore.
(Light Crossbow Attack: 14 Damage: 13 piercing)