Ben:

Sighing as their ruse becomes undone, Ben moves back over behind the others that they might be covered by his protective auras, but he is too far away for a melee attack.  

Instead, he touches his mirrored amulet and says, “May thee be judged by the ugliness of thy spirit, if not by thy revolting countenance.”

Holy light spikes down from above, threatening to burn the evil giant.

Sacred Flame:  DC 15 Dexterity Save to avoid Radiant Damage:  4

Fomorian: DC13 Strength Save or be restrained for 1 minute: 13

"Aw no!" Titaani cries out in disappointment as her spell ends. "We almost had her!"

Furious, the little gnome throws two crackling beams of eldritch energy the giantess's way: Eldritch blast 1: 20 Damage: 8 Eldritch blast 2: 14 Damage: 12

Matilda raced back north Slashing at the Giants calves and Achilles tendons in an attempt to bring it down...then slipped under the table out of sight....

Attack: 9 Damage: 7 + 7 Sneak Attack.

Action Surge- 25 Damage: 7

Bonus Action- Hide.

Pud shoots a nervous smile at the giant. He flinches as Titaani's blast arcs towards the giant. Pud drops the tiny piece of stone that he tinkered to smell like cake and steps back a few paces to create some space.

Pud whips out his multitool spell focus and launches an eldritch blast of his own.

Move: move out of melee range, west down the hallway.

Action: cast Eldritch Blast.

Eldritch Blast 1: 12 to hit for 4 damage

Eldritch Blast 2: 17 to hit for 5 damage

( Move Sneak Attack to the one that hit.)

Pud races west, releasing two beams of crackling energy toward the giant behind him. One hits, doing minor damage.
Titaani releases two similar beams, both hitting the fomorian's back, searing her somewhat more seriously.
Matilda slashes her blade deeply into the giant's ankle before ducking back. (Matilda cannot quite make it back to the table, but she can hide behind Horatio's giant leg. I'd call for a Stealth roll, but I think the giant has her eye on others right now...)
Ben turns and steps in front of Pud, calling down a flamelike radiance upon the giant. DC 15 Dexterity Save to avoid 4 Radiant Damage: 5 (Let me know if you want Ben to get any closer.)

The giant hollers with rage and pain as the blows hit her from all angles. She spins and focuses her attention – and her deformed eye – upon Horatio:

Greatclub Attack vs. Horatio: 22. Hit: 22 bludgeoning damage.
Evil Eye vs. Horatio: Horatio: make a DC 14 Charisma saving throw; take 38 psychic damage on a failed save, or half as much damage on a successful one.

Everyone may act!

Greatclub Attack vs. Horatio: 14. (Disadvantage roll)

Ben:

With an opening now presenting itself to get into close combat, Ben engages the giant and swings his Longsword twice!

(On a hit, he will use a first level spell to smite).

Longsword:  Attack: 19 Damage: 4

Longsword:  Attack: 16 Damage: 7

Smite if applicable:  8

Matilda continued slashing with her magical blade, moving her carving knife into her following hand then moving 20' South to stay out of range.

Attack: 19 Damage: 10

BA- Attack: 12 Damage: 4

Move 20'South- Fancy Footwork to avoid AoO.

Titaani will shoot her with eldritch blast again: 

Beam one: 25 Damage: 4

Beam one: 26 Damage: 4

Elkhorn seems energized by this battle. Using his previous feint (3) to his advantage, he aggressively dives into the fray with his longsword:
Longsword Attack #1: 16. Hit: 14) slashing damage
Longsword Attack #2: 14. Hit: 13) slashing damage

Titaani blasts the back of her head with a double beam of pure crackling energy. (Crit damage: +[4)

Matilda pops out of hiding to stab the giant before carefully retreating south.

Ben steps in, but is swatted off-balance before he can land a blow.

Horatio and Pud may act next!

(Sorry - something weird going on with the formatting of that crit roll. I edited it like a dummy and triggered the banner. Elkhorn's original roll was a single hit for 16 damage, which I'm going with.)

The giant is bloodied – badly wounded, furious, and screaming bloody murder.

Horatio and Pud are up!

Horatio staggers from the psychic blow, but manages to literally shrug off some of its effects (( Bonus Action: Second Wind: 16 HP restored = 42/60 )). He then lays into the Giant once more. "Can't eat cake without teeth ya' filthy monster!" 

(( Action 1: Unarmed Attack: (NAT 1) 9 to hit, 11 to damage ))
(( Action 2: Unarmed Attack: (NAT 20 ?!) 28 to hit, 15 to damage - includes +3 from Giant's Might d6 ))

Pud can see all these hits landing so he continues to pour it on. He's inspired by the success of Titaani's eldritch blasts so he launches two more of his own. He follows that up by getting Rizzo into the action and directing her to launch an attack of her own.

Action: Cast eldritch blast.
-Blast #1: 22 to hit for 4 damage
-Blast #2: 24 to hit for 7 damage

Bonus Action: Direct Rizzo to launch force attack. 14 to hit for 5 force damage

(( The Giant will continue to take Disadvantage on one attack per round until Horatio becomes unconscious ))

Horatio jumps and clobbers the giant across the jaw with a heavy blow, but it is Pud's twin beams that finally take it down. Elkhorn jumps out of the way to avoid being crushed by the massive body. Rizzo is left only to prod a slain fomorian on the floor. 

Combat is over. The giant is dead. Elkhorn dusts himself off with a grim, satisfied smile and nods confidently. "That's how you take down a giant."

What do you do next?

Horatio begins to search the body of the slain Giant, in part to ensure it is actually dead, and also in part to see if it has any of the keys the group have been looking for. He voices this thought, "We uh... we should check it for keys and stuff... and to make sure it is dead dead."

Ben:

”This has been a pretty crazy day.  I’m going to have some of that soup,” he says, walking over to the tureen.

Titaani gingerly steps over the giant's body and runs towards the group's artificer. "Pud! I saw you do the thing I do! How did you do that? Are you also a servant of Titania the archfey? Why didn't you tell me sooner?"